People are, for the most part, very effective capital managers at a personal level. You paint with the wrong brush with your insinuations about sub-prime borrowers since it was the lenders who were the more irresponsible party in that fiasco, hoodwinking both borrowers and investors.
Given the trend towards greater automation in the future there will be less and less need for workers but no corresponding decline in the need for income. There are a few ways to resolve this problem, increase welfare, make work projects, war, genocide, pandemics etc. but none of these are really satisfactory resolutions to the real problem, which is income in a capitalist market economy with not enough real jobs.
One answer would be to move from an employment income economy to an investment income economy. The consumer as investor as opposed to the consumer as worker. This, of course, would require a vast redistribution of capital shares, something which could be accomplished without undue disruption by a long term program of share purchases of corporate stock by the government. There would be no need for the government to gain a majority stake unless compelled by national interest or management malfeasance.
The people/shareholders would receive a share of the dividends as income.