Ask HN: Little knowledge a dangerous thing?

I have been learning(trying to be an expert) about new technologies for more than a year now. But, I have not learned any technology to its core or rather map its real implication in real life. I am interested in almost all domains of computer science - ML, AI, Distributed Computing, Browser networking, Game development, IoT, Web development and what not. But, what I have been doing for the last one and a half year is just reading about them and try to do some basic project only to start doing the same (diverge) when I read about other domain which seems interesting to me. What should be done to streamline things so that I could learn a technology in depth? How do people working on different domains learn all things and still be an expert in those domains?