I think they're just trying to say that your best bet for a good salary and variety of places to live would be to choose something modern (and in demand) and th

I think they're just trying to say that your best bet for a good salary and variety of places to live would be to choose something modern (and in demand) and then stay up to date on as much as you can so you can always stay mobile. Focusing on only one technology is a bad idea as most modern technologies have definite cycles.