Putin and MBS (and Kim) know how to manipulate Trump with flattery and feeding his massive, fragile ego. Putin wants Ukraine and he already owns Trump. If Trump is elected, he’ll cut off aid to Ukraine and hand them over to Russia. If Putin bails him out trhough some back-channel means (no doubt aided by Manafort’s connections with Russian intelligence), the payback is already baked in. Nobody is expecting Trump to pay them back in cash.
I’m not saying that Trump will get bailed out by the Saudis. But the fact that it hasn’t happened yet doesn’t mean it won’t. It would have to be something that’s not easily traceable. And it wouldn’t be like a loan with a contract and terms for repayment. In fact they wouldn’t ask for repayment. They’d tell Trump how unfairly he was being treated and they just couldn’t stand seeing the injustice being done to such a great and powerful leader who did nothing wrong.