All AFC players will leave eventually, some to better paid jobs, most not. Most of the ones listed here have left to better paid jobs if not necessarily better "career" options.
Severin, Nicholson, Hart, Miller, Kerr, Anderson, Mulgrew all moved to bigger pay pokes, not a lot to be done there. Some just didn't cut it where they went, that's just tough titty no being good enough. Is a couple of seasons on the bench with double or treble your wages worth it in a game where regular matches is hugely important?
It isn't a straightforward situation but there do appear many more examples where the move has not worked out.
So, hope the extra dosh was worth it.