As said, some schools employ 'their own' as they are a known quantity. these are invariably the larger modular schools. however, you maybe the best instructor since sliced bread, but if there isn't a job for you not much you can do about it.
there are plenty of other schools out there and if you're prepared to travel a bit you shouldn't have too much trouble finding work.
one of the bad things about working for one of these large-ish schools is that it take quite a while to build up a student base and you can spend a few months scraping by on trail flights. my first job was at a wee school oop norf and it was only me and the CFI. as a result all the existing students were mine to teach from day one. makes paying the bills a bit easier.
the rating may seem a lot of money, but ask yourself how much flying six grand will buy you and how much flying you will do as an instructor. suddenly it doesn't seem that expensive anymore.