All shortages eventually self-correct, but sometimes there is a window of opportunity to profit from even a temporary supply/demand mismatch. This occurs when you catch the very beginning of the shortage and move up, safely out of the most vulnerable zone, before the correction kicks in. Then it may be too costly to replace you with someone else, even if they are "lower-priced". Unfortunately, that timing requires a good deal of luck, because what pilots have to sell is a very perishable commodity.