The pardon power is constitutionally absolute and unreviewable — the president can pardon for any reason, or none. Some people dislike that, but I personally like it, because it acts as an ultimate safety valve on the state’s ability to persecute an individual.
The question is more "why would the President self-immolate themselves politically for someone who appears to have minimal actual political capital, especially now that they're broke?"
Presidents generally don't suffer much from pardoning the wrong person.
There's maybe one President that didn't get elected because of his use of the pardon. But then, Ford wasn't elected President or Vice President before he pardoned Nixon either.
Otherwise, I'm not aware of a pardon so controversial that it became a major campaign issue. And for a second term President, there's not really any downside.
Because the pattern they usually follow is to pardon the questionable cases (personal friends, people with financial ties to the President, etc.) just before they go out of office.
And in exchange for this "safety valve" you get the potential for absolute and unreviewable corruption by giving one person the authority to arbitrarily override the judicial branch at will. And to do the same with the legislative branch through executive order.
If America mistrusts government so much that it wants the President to be a de facto monarch, it should just drop the pretense at being a republic and have a monarchy already. Or make the oligarchy official and elect a CEO in chief. At least then there's only one head for the CIA to put a bullet into.
The "state" being the federal government in this case and not any individual state. The president cannot pardon state-level offenses, that is at the discretion of that state.
Yeah man, everybody knows this. The question is why would any president BOTHER pardoning SBF? It's an idiotic move. Literally no one is defending SBF besides his lawyers