Bernie Madoff had the largest fall from $65 billion estimated at peak to $17 billion at time of arrest then dying in prison.

Changpeng Zhao of Binance will be the richest person in the US, and probably ever, to do time in prison after conviction, but his wealth won't be impacted and it is only a few months, so hardly much Finding Out involved.

Sam Bankman-Fried is potentially an even bigger Find Out than Madoff, because unlike Madoff who maintained a large estate even after going to jail, SBF has gone from around $24 billion to $15.5 Billion at time of arrest, to now close to zero on paper as almost all his wealth was tied up in FTX and crypto and it was "all" siezed as part of his conviction and the FTX winddown. Now that said, he probably has a lot of crypto stashed in cold wallets somewhere that have appreciated substantially since his arrest, so it is hard to know how much he would be worth if he ever got access to them, but as I understand it he is basically banned from using computers and facing over 100 years on his sentence, so he better be putting in a lot of good behavior of he ever hopes to see any of that secret stash again.