Yeah, but that was a classic stock bubble. There's a lot of debt in this one. Think of all the debt for the data centers and margin for stocks is at record high. You just lost one the of the biggest buyers of data center stocks at a time they desperately need to keep their stock prices up in order to borrow more.
I guess you can say his awareness of his risk situation was poor. There is no way you can sustainably run 300%+ leverage on stocks , unless you eventually cut back, which he had failed too until he was forced out . This is not like leverage on bonds . It was not a matter of if, but when.
This bubble has both, the margin in stocks is keeping share prices of datacenter companies afloat as they try to borrow more. The growth from the borrowing keeps the share price afloat. Now a massive buyer of datacenter company equities is out. There is circularity to how the debt is reinforcing each other. When one part of the cycle stops spinning it could reinforce a drop in the other.