Although it might sound strange, there are large numbers of FR pilots who stay because they are quite simply well inside their comfort zone and just can't be asked to put up with the upheaval of moving.
I left them nine years ago but regularly bump into guys I flew with; despite the fact that they whinge and moan about how awful it is, none of them have seriously considered leaving, either because they believe they will take a drop in salary or because it will involve a change of base.
ZeBedie's observations apply here - until this year we haven't hired one single FR pilot at my base, and only a small handful throughout the rest of our network.