If they reported tomorrow Elon died from a drug overdose would you suspect foul play?

0%, straight-up killing a billionaire would freak out other billionaires, and Elon is the most easily discredited person ever. A character assassination would be more effective than an actual assassination.

Zero chance, it would scare all the other wealthy narcissists and they would rug pull the administration. There just isn't enough history of that kind of corruption to do it yet.

Canceling all his contracts and maybe putting up barriers to xhitter is far more likely.

I'd say 0 but the chances of it happening to anyone are probably not actually ever 0%.

The US doesn't typically defenstrate to assassinate anyone. We use guns. Or make it look like an accident, so he is more likely to OD on drugs than anything. Plausible deniability.