This is something that scares me too. It's a very depressing line of thought, by that logic you couldn't ever hope to escape the normalfags.
However I think it's not that hopeless. The first time the web started attracting normies, we were all naive. We thought it would be good. We thought the growing interest in the web and tech would bring solutions to all the bad things about it (in some cases it did, like the increase in speeds over the years) without ruining any of the good. Turns out we were wrong, and the normies don't respect what we respect, they're like pigs at a fancy banquet.
The second time around, if there is one, we will know better. Most people will have experienced the problem firsthand, so the culture will be far less inclusive. For instance, back around 2002 and earlier, I remember always feeling excited when I heard about my hobby/vidya/forum/software becoming popular and I'd tell people about it when appropriate. These days I don't ever mention shit like 8ch, cock.li, and so on without extreme vetting. I can't be the only one. This, plus a lack of willingness to spoonfeed the more complicated technical aspects, will keep normies at bay in future endeavors.
Well, it's not so transient that it's gone tomorrow. They can stay popular for 2-3 years, and linger around for another 5 give or take. On the one hand it's a waste to invest your time in something that won't last a decade, but on other hand it's long enough to push a project or two out the door so why not. Some of them (not all) do enable you to quickly produce applications that would otherwise be very labor/time-intensive to do.
What is the TAOCP way of building an ride sharing app with iOS, Android and WP support, for instance? Serious question, if this is a conceptual leap that I'm missing I'd love to learn.
As for "investing a lot of time" into them, not sure about that. A lot of people seem to learn them easily enough, so either these things aren't that hard to learn, or there's some real fast learners out there, or I dunno what else. One thing I know is that reading the docs doesn't ever work if you don't already have deep knowledge of software concepts, all the hipster frameworks like to pretend that they're easy and anyone can pick them up, but in practice the barrier for even comprehending the docs is high.