Quantum mechanics took a left turn at some point after Einstein quantized light, though. It wasn't his idea to turn particles into probability waves. Personally, I don't fault Einstein for thinking it was a little bit too bizarre. Afterall, Einstein was very logically oriented, and there are aspects of quantum mechanics that seem inconsistent with relativity, so it is an easy step to say quantum mechanics must be wrong.
The problem is that when you start talking about probability, you are in the netherworld. Personally, I believe that probability is just a way to account for factors you cannot understand. We filter out all of those that we can understand and incorporate them into the theoretical structure. But we're still left with a certain amount of arbitrariness, and if it follows a normal distribution, then the likelihood that you are going to isolate the factors that give rise to it is slim. So we just deal with it using probability theory. I don't have any problem with that, but quantum mechanics goes one step further and says that it is not simply a residual that we can't explain. It's part of the structure. To me, that is a hard thing to accept. And obviously, it was for Einstein, too.
I suspect that someday, the notion that a particle is nothing but a probability wave will be relegated to the trash bin. We'll probably be long dead by then, though. It took almost 2,000 years to put the last nail in Aristotle's coffin. Once we did, it opened up a whole new series of insights, though. I think something like that has got to happen for quantum mechanics in order to get to the theory of everything.
There doesn't seem to be too much interest in getting to that point, though, right now. Your average physicist says that quantum mechanics is good enough. Those that don't agree are even further in left field, though, wasting their efforts on the even more bizarre string theory.
String theory doesn't contradict quantum mechanics in any way - it is a variant of quantum theory that attempts to incorporate gravity (and is hence extremely complex). I don't think any physicist really says quantum mechanics is "good enough" - all physicists realize that standard QM doesn't address gravity (and most don't work in fields that require one to do so).
Definitely hard-to-understand stuff, but QM works, no doubt about that.
"Quantum mechanics took a left turn at some point after Einstein quantized light, though. It wasn't his idea to turn particles into probability waves."
I know you're using shorthand. But of course it was Planck who "quantized" light. Or rather his math. E just tried to explain it.
And the irony of E getting a Noble Prize for that, since he never believed that light was a particle, but a wave. (And not an unmeasurable wave.)