Indeed the punishment is light regarding the hacker's harm to investors and traders. But, it's better to be jailed than not. So as to relieve the grieve of the affected people. However, his solicitor may have helped in breaking the term down to 5 years. Added to the recovered Bitcoin.
The hacked Bitcoins belonged to the exchange and its users. However, the exchange took action afterward by compensating the affected users with a BFX token.
https://support.bitfinex.com/hc/en-us/articles/4417401349657-2016-Security-Breach-Bitcoin-Recovery-Frequently-Asked-Questions-FAQOn August 2, 2016, Bitfinex suffered a security breach where 119,755 BTC were stolen. To compensate customers for resulting losses, Bitfinex credited BFX tokens to customers at a ratio of 1 BFX to 1 US dollar lost. Bitfinex honoured its commitment to repay the losses. Within eight months of the security breach, all BFX token holders had their tokens redeemed at 100 cents on the US dollar or exchanged their tokens for shares of the capital stock of iFinex Inc.
All BFX tokens were destroyed as a part of the repayment process. Additionally, Bitfinex created a tradable RRT for certain BFX holders that converted BFX tokens into shares of iFinex.
Coincidentally, it's as if the government's interest rose the moment the value of Bitcoin increased which made the hacker a billionaire. Hopefully, they'll sell the coins on auction or hold it for their benefits.
This delay in returning the funds actually worked out in Bitfinex's favor since the value of the Bitcoin during the hack was under $100 million, but now it's worth billions. The government can’t claim ownership because it’s clear from the start that it was Bitfinex’s Bitcoin that was hacked. It just needs to go through some legal processes before Bitfinex can reclaim it. Now that the hackers have been sentenced, I think they’re close to getting it back -- whether in Bitcoin or fiat, depending on the authorities’ decision.