Loyal workers are selectively and ironically targeted for exploitation
Being a worker is being underpaid, to varying degrees. Another way to put it is "the most valuable employee makes the most impact for their salary", so the tendency is to maximize the former and minimize the latter."Loyalty" is a manipulation game. The only true loyalty is to #1, but most honest people don't even do that.One primary way to get ahead is be in-demand, court many offers, and play offers off each other in an ego-respecting manner within whatever the market will bear. 
Raises rarely happen, so it's usually better to switch jobs every 1.5-3 years.At some point in a high-income career path, switching jobs doesn't have to be as necessary or desirable, and a lawyer and a TC negotiator can help them get more $$$.Furthermore, anyone good will have lots of options and should always be open to other homes if only to window shop. (Never be stuck somewhere miserable or without options.)