No, most low earners are receiving more back in benefits of various types than anything they pay into the system.
Thus if you replace these systems with mandatory investments, you are reducing their available cash.
Thus if you replace these systems with mandatory investments, you are reducing their available cash.
Everyone who gets a paycheck pays their 6% in social security, regardless of income level.
Social security tax is 12.4% on the first $113,700 of wages or self-employment income, and 0% on income from all other sources and wages and self-employment income past the first $113,700, so, no, you don't pay "6% in social security, regardless of income level".
(Note that on wages, but not self-employment income for obvious reasons, half of the 12.4% is paid as 'employer share', so that the employee never sees it, so it might appear, if you look only at wage withholding, that the rate is 6% -- or rather, 6.2% -- but that's not accurate.)