Chris Rock said it best and it has always stuck with me:

"Stop telling kids they can be anything they want to be. You can be anything you're good at, as long as they're hiring."

Surely it's like that line from Rattatuille, "not everybody can become a great chef, but a great chef can come from anywhere"

So in a sense it's true that you can grow up to become anything, but there's an unspoken caveat that the above is only true if you can overcome your own personal economic/societal/mental/physical/geographical obstacles.

That thing is more about collapsing options as time moves on though. When you're a kid you really can be 'anything' ignoring social and economic stuff. The probability curve is pretty open to anything at that point though. Once you're thirty it feels squarely like that is less true and my options are clearer but more limited.

It's scary but also awesome that you have so many open doors as a kid and adults that say this are mostly envying something they've lost and didn't appreciate or see until later