Somewhat related: Social Security.
The SS tax has been increased by 2% to 6.2%. If we assume the same rate of payout is still available in 2053 (my year of retirement at age 66) and my monthly income does not change, I would generate about $6,500.00 in a monthly paycheck from the government. (source:
http://www.socialsecurity.gov/OACT/quickcalc/)
If, instead, that 6.2% was invested in the private sector (stock market), which has, historically, generated 10% investment return per year, then I would have accumulated $1.3M of retirement wealth. If I withdrew the investment income (10% annually) from that accumulated wealth, or almost $11,000/month.
Now, this doesn't have much of a direct tie-in with welfare, but it still jerks my chain that we're forced to participate in this system instead of being able to use that money towards something more.... profitable.