pay to fly, means to pay for working, while you fly passenger for a commercial purpose. Simple.
It is not the same to pay for a degree and education. After all you do it for yourself. Yes, money is out of your pocket, but it's for you.
You pay for CPL IR, it's normal, that is for a training purpose and you don't fly passenger.
About the Type rating, we could discuss about it...years ago airlines used to pay for it, even for the MCC.
Sorry but flying professionnally and paying for it it's nonsense. You lose money, plus your work for others (not really for yourself in that case).
Ok I admit it, we should call it : P2W for Pay To Work. That would be better.