Gambling, like finance, has rules. If I start a casino, and tell everyone that the roulette is fair, and then go ahead and rig it so no one ever wins, then yea, I should be sent straight to prison.

If SBF told everyone loud and clear "hey guys you can give me money and I will use it to gamble on my favorite crypto tokens and play board games with Caroline" then I don't think he would deserve a prison sentence (but he also wouldn't get any customers). It's the deception that makes it a crime.