He kept 150,000 Bitcoin.. Today they'd be worth over $50M. If you stole a stack of stock certificates on a day when they were only worth $10 and were arrested on a day when they were worth $100, you couldn't just pay back $10 in cash and walk away with the stock, why should BTC be any different?
Failure to repay is subtly different from going out and stealing in the traditional manner. If you fail to repay stock and get super lucky with the value I think you should be able to pay cash+interest+penalties* and walk away. (And play roulette next time, less likely to end in jail.)
They're not going to demand less money if the stock goes down, are they?
*penalties perhaps meaning you pay $30 plus interest
Well, possibly it could be rehabilitation, but what if rehabilitation fails and they offend again? Do you just layer on more rehabilitation each time, or do you eventually decide on punishment at some point?