Do you know of any who "trade" because it is a thrill or a challenge, and are billionaires? Personally? If not, unless they have given a specific reason as to why they do it, we do not know their reasons. You are assuming. Maybe those paper billionaires are in serious trouble with their hedge funds, and are trying desperately to not lose their shit. Oh, wait, hedge funds...It is not THEIR money, it is OPM.
Overnight, calm down, the question is, they themselves are rich beyond measures, WHY DO THEY CONTINUE to trade?