It's not that simple. Many LCCs have regional bases. No money in the world will tempt many people to move to a legacy who tend to gravitate around one or two hubs. BA at London, AF at Paris, KL at AMS. LCCs also tend to be quite well paid and give you options of moving around the network without the hassle of commuting. Ryanair and easyJet have dozens of bases. I don't see any evidence of LCCs struggling to find enough pilots.