Physicists already understand quantum mechanics. There are open questions, but it's no longer the case that the physicists themselves just stand slack-jawed at it. Every field has open questions, and nobody says "Nobody understands DNA" or "Nobody understands polymer chemistry".

Quantum mechanics attracted a lot of mystical woo early in its development, because it was so deeply unfamiliar from classical physics, but we've been at it for over a century now. We've moved way, way past the weirdness of quantum erasers and other examples that get promoted in pop science books. As I said, that doesn't mean all of the questions are answered, but a lot of questions are answered. You just can't understand the answers by expressing them in purely conventional terms, as pop science books try to do.

So physicists don't come out of school wearing pointy hats and feeling like the keepers of arcane knowledge. They can do quantum mechanics and apply it. That's not forbidden knowledge. It just takes work. Nobody ever promised you an understanding of physics from comfortably reading about it at a middle-school level, any more than you'd expect to learn dishwasher repair or glassblowing just from breezy introductions to it.

The information is accessible, and lots of "Quantum mechanics for dummies" books can actually give you a good handle on it. Yes, it takes math, but not very advanced math. Yes, you have to learn a new language, but that's to be expected. Novel ways of viewing the universe require new ways of talking about it. It's right there, publicly accessible.