Look at where you actually spend your time in a given day. Is it spent in a testing framework? Cleaning up data? Creating APIs? Reviewing code? Installing a CMS? Setting up CI workflows? Writing CSS? Configuring Webpack?
Spending time in fringe technologies is like buying shares of AAPL, TSLA, or whatever else is hot right now. It can be fun, and it might be a good investment, but it’s a gamble. On the other hand, those core web technologies are like index funds. Kind of boring, but you can expect them to be valuable in the long term. And for careers, like investing, the long term is where all the interesting stuff happens.