It's simple... Credit.
It's the society we live in now, when my parents grew up they had to save money to go on holiday, now it's "I'll just bung it on the credit card and worry about it later". It's the exact same principle for flight training, why wait 5-6years when I can borrow huge amounts of money and worry about it later.
The banks, airlines, FTOs etc have all taken advantage of this while the average 18-30 year old struggles with the repayments.