It's actually pretty tough to fire people and bring them in at big corporations. I've made some good money training server developers into mobile developers and

It's actually pretty tough to fire people and bring them in at big corporations. I've made some good money training server developers into mobile developers and whatnot simply because these large companies actually do find it more cost effective to retrain current employees than fire and rehire. It's true there are cases where that won't happen, but it is also true retraining and retention happens quite a lot.