stole 4.5 large from him the night before this became public? He didn’t appear angry at all. Also, what bookie is going to give his buddy a line of credit that large without Ohtani’s knowledge? A lot of questions.

I don't know enough about him to judge that.

With the money these guys make? They would have to be idiots to throw a game.

They don't have to throw a game. All they have to do is not cover the point spread. I haven't trusted pro sports for a long time.

They can still be entertaining, though.

their hard earned money.

Generally, the financial incentive for players & coaches isn't there. This isn't 1919 where the promise of 10 grand was 6x the salary of guys trapped working for an owner so cheap that he charged them for laundering their uniforms.
Nobody is going to make 6x of $25 million, if for no other reason than that much money flowing in on one side would raise suspicion to the point of taking said game off the board.
Officials are a separate concern, but they have less influence on the outcome than the players.
That said, Rose didn't need the money, but there's no evidence he took actions to throw any games. And, I say that as someone who disliked Rose, even when I was a kid. He was addicted to the action, not trying to influence outcomes.
The NBA situation with a player making prop bets then leaving the game before the over is different. But even if true, his impact on the game is minor & unlikely to affect the outcome. It just looks bad.

it comes to a point spread.