It's not that it's harder, exactly. It's that your priorities shift quite a lot as you move along. Technical mastery in the sense of "look at this extremely complicated, high effort piece" tends to be the provenance of young people. Young people need to prove themselves and work the chip off their shoulder. They want to keep up with the new, and so they'll try to master whatever looks like the new thing.<p>But then you get to a place where you've done some of that keeping up, and most of the time, it's not going to consume you for the rest of your life. A new thing eventually becomes old, and while learning another new thing can set up a career, you hesitate a little more to bother when you already have things you want to go deeper on. Which means the kind of learning you do is different, less focused on the grind of established courses and more in the space of independent study, integrating a bunch of disparate things into a whole. It shows up in people's brains, too: the current thought is that "crystallized" intelligence peaks much later in life. Young people are fast, old people are wise.<p>I realize now that something I really didn't understand, even as I started my 30's, was how to study things really well. I could be a <i>fan</i> about them, and learn interesting facts, and follow steps, but the really essential thing was to not gloss over it, and to turn the learning into a workout, a thing that engages you while simultaneously being relatively simple and monotonous, just copying things, memorizing things, repeating processes to master them. And part of your repulsion may well be the same kind of feeling that many get at the idea of "working out" - your brain knows that's what needs to be done, your emotions say, why do that, it's so much effort. As a baby it's no issue, you'll do anything if pointed the right direction, and just expend all the energy you have on hand and then sleep it off. But somewhere along the way you both gain desire to save energy, and also to protect an identity of being "the kind of person who...", and other various beliefs. You can't just turn on baby mode and follow along with the nursery rhymes or practice tracing the alphabet. No, you have to say to yourself, "I'm going to turn this into reps and do 30 reps today." It takes some creativity even to start down that path because often the material you want to study is all packaged up in a form that doesn't aid your mastery.<p>But it's hardly as simple as old people suddenly becoming unable to operate a computer. The old can still discuss technical matters, but they aren't self-evidently interesting to know or discuss. Most of them are things to eliminate from life in order to make room for something else.