Wonder why he was only charged with contempt, rather than defrauding investors?

If a judge says you're in contempt, you'll get charged with contempt immediately - all the people required are present.

To charge him with defrauding investors requires a whole different group of people to get involved.

Additionally, those people need enough evidence to have a chance of conviction. "He refused to answer questions about it" is not actually evidence.

^this. The person described here appears like a crook who pocketed millions and stiffed investors, so why just a contempt charge?

In any case, probably not a romantic explorer figure as the clickbaity title suggests.