Is this really possible? Mutual funds vs Whole life insurance?

The calculator is correct. I will copy and paste the returns.

As for the rest of your question: 12% is a bit hight. To be conservative use a 9% or 10% return. Also realize that this does not take into account the affects of inflation.
Initial Deposit: $500.00
Interest Rate: 12.00%
Monthly Contribution: $100.00

2,008 Feb $500.00
2,008 March $606.00
2,008 April $713.06
2,008 May $821.19
2,008 June $930.40
2,008 July $1,040.71
2,008 Aug $1,152.11
2,008 Sept $1,264.63
2,008 Oct $1,378.28
2,008 Nov $1,493.06
2,008 Dec $1,608.99
2,009 Jan $1,726.08
2,009 Feb $1,844.35
2,009 March $1,963.79
2,009 April $2,084.43
2,009 May $2,206.27
2,009 June $2,329.33
2,009 July $2,453.63
2,009 Aug $2,579.16
2,009 Sept $2,705.95
2,009 Oct $2,834.01
2,009 Nov $2,963.35
2,009 Dec $3,093.99
2,010 Jan $3,225.93
2,010 Feb $3,359.19
2,010 March $3,493.78
2,010 April $3,629.72
2,010 May $3,767.01
2,010 June $3,905.68
2,010 July $4,045.74
2,010 Aug $4,187.20
2,010 Sept $4,330.07
2,010 Oct $4,474.37
2,010 Nov $4,620.11
2,010 Dec $4,767.32
2,011 Jan $4,915.99
2,011 Feb $5,066.15
2,011 March $5,217.81
2,011 April $5,370.99
2,011 May $5,525.70
2,011 June $5,681.96
2,011 July $5,839.78
2,011 Aug $5,999.17
2,011 Sept $6,160.16
2,011 Oct $6,322.77
2,011 Nov $6,486.99
2,011 Dec $6,652.86
2,012 Jan $6,820.39
2,012 Feb $6,989.60
2,012 March $7,160.49
2,012 April $7,333.10
2,012 May $7,507.43
2,012 June $7,683.50
2,012 July $7,861.34
2,012 Aug $8,040.95
2,012 Sept $8,222.36
2,012 Oct $8,405.58
2,012 Nov $8,590.64
2,012 Dec $8,777.55
2,013 Jan $8,966.32
2,013 Feb $9,156.99
2,013 March $9,349.55
2,013 April $9,544.05
2,013 May $9,740.49
2,013 June $9,938.90
2,013 July $10,139.28
2,013 Aug $10,341.68
2,013 Sept $10,546.09
2,013 Oct $10,752.56
2,013 Nov $10,961.08
2,013 Dec $11,171.69
2,014 Jan $11,384.41
2,014 Feb $11,599.25
2,014 March $11,816.25
2,014 April $12,035.41
2,014 May $12,256.76
2,014 June $12,480.33
2,014 July $12,706.13
2,014 Aug $12,934.19
2,014 Sept $13,164.54
2,014 Oct $13,397.18
2,014 Nov $13,632.15
2,014 Dec $13,869.47
2,015 Jan $14,109.17
2,015 Feb $14,351.26
2,015 March $14,595.77
2,015 April $14,842.73
2,015 May $15,092.16
2,015 June $15,344.08
2,015 July $15,598.52
2,015 Aug $15,855.51
2,015 Sept $16,115.06
2,015 Oct $16,377.21
2,015 Nov $16,641.98
2,015 Dec $16,909.40
2,016 Jan $17,179.50
2,016 Feb $17,452.29
2,016 March $17,727.82
2,016 April $18,006.09
2,016 May $18,287.16
2,016 June $18,571.03
2,016 July $18,857.74
2,016 Aug $19,147.31
2,016 Sept $19,439.79
2,016 Oct $19,735.19
2,016 Nov $20,033.54
2,016 Dec $20,334.87
2,017 Jan $20,639.22
2,017 Feb $20,946.61
2,017 March $21,257.08
2,017 April $21,570.65
2,017 May $21,887.36
2,017 June $22,207.23
2,017 July $22,530.30
2,017 Aug $22,856.61
2,017 Sept $23,186.17
2,017 Oct $23,519.03
2,017 Nov $23,855.22
2,017 Dec $24,194.78
2,018 Jan $24,537.72
2,018 Feb $24,884.10
2,018 March $25,233.94
2,018 April $25,587.28
2,018 May $25,944.15
2,018 June $26,304.60
2,018 July $26,668.64
2,018 Aug $27,036.33
2,018 Sept $27,407.69
2,018 Oct $27,782.77
2,018 Nov $28,161.60
2,018 Dec $28,544.21
2,019 Jan $28,930.65
2,019 Feb $29,320.96
2,019 March $29,715.17
2,019 April $30,113.32
2,019 May $30,515.46
2,019 June $30,921.61
2,019 July $31,331.83
2,019 Aug $31,746.14
2,019 Sept $32,164.61
2,019 Oct $32,587.25
2,019 Nov $33,014.12
2,019 Dec $33,445.27
2,020 Jan $33,880.72
2,020 Feb $34,320.53
2,020 March $34,764.73
2,020 April $35,213.38
2,020 May $35,666.51
2,020 June $36,124.18
2,020 July $36,586.42
2,020 Aug $37,053.28
2,020 Sept $37,524.82
2,020 Oct $38,001.06
2,020 Nov $38,482.07
2,020 Dec $38,967.90
2,021 Jan $39,458.57
2,021 Feb $39,954.16
2,021 March $40,454.70
2,021 April $40,960.25
2,021 May $41,470.85
2,021 June $41,986.56
2,021 July $42,507.42
2,021 Aug $43,033.50
2,021 Sept $43,564.83
2,021 Oct $44,101.48
2,021 Nov $44,643.50
2,021 Dec $45,190.93
2,022 Jan $45,743.84
2,022 Feb $46,302.28
2,022 March $46,866.30
2,022 April $47,435.97
2,022 May $48,011.33
2,022 June $48,592.44
2,022 July $49,179.36
2,022 Aug $49,772.16
2,022 Sept $50,370.88
2,022 Oct $50,975.59
2,022 Nov $51,586.34
2,022 Dec $52,203.21
2,023 Jan $52,826.24
2,023 Feb $53,455.50
2,023 March $54,091.06
2,023 April $54,732.97
2,023 May $55,381.30
2,023 June $56,036.11
2,023 July $56,697.47
2,023 Aug $57,365.44
2,023 Sept $58,040.10
2,023 Oct $58,721.50
2,023 Nov $59,409.72
2,023 Dec $60,104.81
2,024 Jan $60,806.86
2,024 Feb $61,515.93
2,024 March $62,232.09
2,024 April $62,955.41
2,024 May $63,685.96
2,024 June $64,423.82
2,024 July $65,169.06
2,024 Aug $65,921.75
2,024 Sept $66,681.97
2,024 Oct $67,449.79
2,024 Nov $68,225.29
2,024 Dec $69,008.54
2,025 Jan $69,799.63
2,025 Feb $70,598.62
2,025 March $71,405.61
2,025 April $72,220.66
2,025 May $73,043.87
2,025 June $73,875.31
2,025 July $74,715.06
2,025 Aug $75,563.21
2,025 Sept $76,419.85
2,025 Oct $77,285.04
2,025 Nov $78,158.89
2,025 Dec $79,041.48
2,026 Jan $79,932.90
2,026 Feb $80,833.23
2,026 March $81,742.56
2,026 April $82,660.98
2,026 May $83,588.59
2,026 June $84,525.48
2,026 July $85,471.74
2,026 Aug $86,427.45
2,026 Sept $87,392.73
2,026 Oct $88,367.65
2,026 Nov $89,352.33
2,026 Dec $90,346.85
2,027 Jan $91,351.32
2,027 Feb $92,365.84
2,027 March $93,390.49
2,027 April $94,425.40
2,027 May $95,470.65
2,027 June $96,526.36
2,027 July $97,592.62
2,027 Aug $98,669.55
2,027 Sept $99,757.25
2,027 Oct $100,855.82
2,027 Nov $101,965.38
2,027 Dec $103,086.03
2,028 Jan $104,217.89
2,028 Feb $105,361.07
2,028 March $106,515.68
2,028 April $107,681.84
2,028 May $108,859.65
2,028 June $110,049.25
2,028 July $111,250.74
2,028 Aug $112,464.25
2,028 Sept $113,689.89
2,028 Oct $114,927.79
2,028 Nov $116,178.07
2,028 Dec $117,440.85
2,029 Jan $118,716.26
2,029 Feb $120,004.42
2,029 March $121,305.47
2,029 April $122,619.52
2,029 May $123,946.72
2,029 June $125,287.18
2,029 July $126,641.06
2,029 Aug $128,008.47
2,029 Sept $129,389.55
2,029 Oct $130,784.45
2,029 Nov $132,193.29
2,029 Dec $133,616.22
2,030 Jan $135,053.39
2,030 Feb $136,504.92
2,030 March $137,970.97
2,030 April $139,451.68
2,030 May $140,947.20
2,030 June $142,457.67
2,030 July $143,983.24
2,030 Aug $145,524.08
2,030 Sept $147,080.32
2,030 Oct $148,652.12
2,030 Nov $150,239.64
2,030 Dec $151,843.04
2,031 Jan $153,462.47
2,031 Feb $155,098.09
2,031 March $156,750.07
2,031 April $158,418.57
2,031 May $160,103.76
2,031 June $161,805.80
2,031 July $163,524.86
2,031 Aug $165,261.10
2,031 Sept $167,014.72
2,031 Oct $168,785.86
2,031 Nov $170,574.72
2,031 Dec $172,381.47
2,032 Jan $174,206.28
2,032 Feb $176,049.35
2,032 March $177,910.84
2,032 April $179,790.95
2,032 May $181,689.86
2,032 June $183,607.76
2,032 July $185,544.83
2,032 Aug $187,501.28
2,032 Sept $189,477.29
2,032 Oct $191,473.07
2,032 Nov $193,488.80
2,032 Dec $195,524.69
2,033 Jan $197,580.93
2,033 Feb $199,657.74
2,033 March $201,755.32
2,033 April $203,873.87
2,033 May $206,013.61
2,033 June $208,174.75
2,033 July $210,357.50
2,033 Aug $212,562.07
2,033 Sept $214,788.69
2,033 Oct $217,037.58
2,033 Nov $219,308.95
2,033 Dec $221,603.04
2,034 Jan $223,920.07
2,034 Feb $226,260.27
2,034 March $228,623.88
2,034 April $231,011.12
2,034 May $233,422.23
2,034 June $235,857.45
2,034 July $238,317.02
2,034 Aug $240,801.19
2,034 Sept $243,310.21
2,034 Oct $245,844.31
2,034 Nov $248,403.75
2,034 Dec $250,988.79
2,035 Jan $253,599.68
2,035 Feb $256,236.67
2,035 March $258,900.04
2,035 April $261,590.04
2,035 May $264,306.94
2,035 June $267,051.01
2,035 July $269,822.52
2,035 Aug $272,621.75
2,035 Sept $275,448.96
2,035 O