Are You an Expert in a Certain Technoledge?

As an engineer, is always easier to market yourself as like, expert on a particular technoledge. You might get paid really well to join start up if you know exactly the problem. But i would say, as a career that technoledge might die or aknowledge my evovan, then you are under water or the other side. And what if you want to be interpretor and you want to beat your own start, if you only know fromtantwy? So i thinki look from that perspective of ownership, right? Do i understand the fool busness, but that's me. I want to try to at least have a likea idea of things, and to