Social Security relies on individuals paying into the program, welfare does not.
So if everyone stopped paying taxes, welfare would continue?
Because social security was supposed to be based on a trust that people paying into it during their working years would get it back during their retirement years.
The government started using that money and pilfered the fund to where it's almost exhausted. Add to that, that there are currently more pulling out of it than putting in to it, and the people working now, are paying for the people who are receiving now. the trust is on it's way to being insolvent.
Welfare was never based on a trust, but always just a direct tax, which means it cant go bankrupt because there was never any fund, or trust in which people were to draw off of.