The fact that there are no easy answers doesn’t mean there’s not a problem. It sounds like we actually completely agree on the nature of the problem. You’ve proposed some solutions, but frankly I don’t think they’re very good, nor do I think you really want to implement them, so I don’t see much point in arguing positions nobody supports.
There are people who hunt down ill-gotten gains, passed through generations, and make attempts at some sort of restorative justice. They’re Nazi hunters. The records were better then, and not as much time has passed, so it can and is done. Lots of stories where perfectly innocent Germans hand back stolen paintings they got from their Nazi relatives, and so on. You very correctly point out that money has no label on it saying “I was earned unjustly” – and certainly much of the ill-gotten gains have been diluted to the point where they cannot be reclaimed. But as the Nazi hunters have taught us, sometimes the wealth follows a straight enough line to follow. Not all of the wealth, not even a fraction of the wealth. But if it does, I don’t have a problem following the line.