The wealthy did not sell assets at above market prices, they in fact sold them at bellow market prices. Remember when they were trying to sell assets, they were exchanging these for cash. The problem was that the cash that they were getting in exchange had above market returns.

What was happening during the financial crisis is that even the safest private assets were risky illiquid and had low expected returns.

Some estimates say that marginal "safe" private assets had a expected real returns of around -4% after adjusting for risks and liquidity.

But since central banks were not aggressive enough, not creating enough inflation and unwilling to use negative interest rates, the returns on cash was like -1.8%, way above what you could get with safe and liquid private stores of value.

Investors wanted to get their hands on this government paper having above market returns so they attempted to sell private assets and stockpile cash. This is clearly visible in the shooting up of excess reserves in banks. Investors were hoarding cash. The low inflation and relatively high 0% interest rates (compared to market rates) was a huge subsidy to those who wanted to get out of the private markets, stop investing in the real economy and hold government paper to protect their savings.

Destruction of the economy, throwing workers to the curb was basically subsidized. Investors were being shielded from the markets by the government. They kept their government paper promises to be redeemed in the future when private markets looked more favorable. Central banks allowing cash to have returns above market put the private investment markets in a gridlock and economic activity slowed down significantly.

Cash is effectively an IOU from non cash holders to cash holders. This means that the above market returns investors got by hoard cash was a implicit subsidy from poor unemployed to rich savers. The unemployed and underemployed effectively subsidized the destruction of their own jobs.

When jobs returned and workers could buy stuff again, the savers' cash, now worth above what they could have gotten in the private markets, also flowed back into the asset economy and bid assets prices up and made them more expensive to those who were just starting to have money again, at just the time when they were buying again. People who had been the poorest during the crisis were effectively paying the bill for the subsidy that destroyed their past careers.

It is crucial that central banks run a counter cyclical monetary policy and that inflation is kept higher than usual during a crisis to avoid all this from happening. It is crucial that cash doesn't become a subsidy to divestment and crowd out private investment like it did. When the private markets return -4% (risk and liquidity adjusted), government paper should return less than -4%.