The time behind bars seems wrong on many levels but I'm having a hard time understanding/sympathising the guy's position beyond the "contempt of court is a poor fit for assigning punishment for this kind of thing and you can't just keep someone locked up on suspicion they did something wrong you have to use a real pre-existing law and prove it".

Losing your entire fortune isn't impossible by any means, even coincidentally right when your wife announces she wants a divorce, but you'd think he'd have a more forthright explanation for why there is no record (person, investment contact, business record on the other side, etc) to point to anywhere for his 2.5 million dollar exchange. The only reasons I can think to not are ones that also explain why he'd rather take contempt of court charge than say what happened (illegal investments, purposefully losing the money, hiding the money, trying to do one of these things and being conned). For that reason I definitely feel the guy shouldn't have been jailed but I don't really feel bad for the guy as in he got screwed by bad luck or something.

I'm curious what sort of bad investment he made that left no paper trail as to where the money went.

Did he have no evidence whatsoever? Or was the evidence unconvincing?

The judge who released him also noted that they believed Mr. Chadwick could pay the owed amount but that it was clear keeping him in prison wasn't going to make that happen