Just being on the books at a top tier club will earn a player more money than we would pay in total (appearances, win bonus final place etc). The players mentioned above were all of an age where the risk factor to their overall careers were at worse, minimal. If things don't work out they're still better off financially and they just drop a level to their previous roles at roughly a similar paying club to ourselves.
Conversely there's many a case of a youngster whisked away to a bigger club where a career becomes unstuck. During their late teens/early twenties they don't gain enough experience (game time) at an appropriate level. I'm not sure if Fitz is the best of examples but I suspect another season or two with us and his career may have progressed in a higher trajectory.