That has never been an easy question. Learning is hard work. If your parents/school didn't force you to learn it as a kid, then odds are your attempts to learn something new as an adult fail. Many adults take up a musical instrument, or foreign language -only a few learn more than the most basic phrases, these are the most common things for adults to attempt and the track record is poor. Sure adults who know C++ (a tiny subset of adults) might learn Rust with high success - but the hard part is learning to program not the syntax of the language.

A desire to learn generally only gets you to a superficial level before you get bored and realize there is a lot of hard work before you could get a useful level of knowledge. Getting deep requires years of focused effort and that almost always means forced effort. The few adults who learn a musical instrument or foreign language prove the point.