About 20 years ago, I stopped studying quantum mechanics because it frustrated me so much; I wanted to understand the "quantum regime." After coming back to study more, I've made a lot of progress. I always hated that some said quantum mechanics was weird, or if you think you understand it, you don't. You just need to know there's a difference between seeking ontology of the subatomic, Vs the epistemic adequacy of quantum mechanics. While I'm nowhere near done studying physics overall, I'm still proud of my progress.