Warren basically went bankrupt during financial crisis. If he was not a league of his own, he would have nothing today (nothing in his terms, still would be a multi millionaire of course). Imagine what happened back then, rules were changed to allow managers estimates the value of their holdings themselves, removing mark to market.
If he was marked to market, bye bye his billions.
For what it’s worth, every financial institution would have gone bankrupt if it weren’t for government intervention on many levels. The financial crisis was THAT bad. When Paulson let Lehman go under that was the end, even though the Lehman bankruptcy went quite smoothly.
Likely we would have entered into a proper depression as Main Street couldn’t get loans either.