Depends where your from
I have met a Kuwaiti and an Omani who for whatever reason didn't get in to the Cadetships offered in their home countries. They were both told that if they went out and got a fATPL, type rated on a 737/320 with 150-250 hours they would get an interview. The airlines also said they would have to pass the same assesment as all other direct entry FO's but the TT minimum would be waived because they were locals.
Remember I said even the locals don't get a guarantee after P2F. Now these guys weren't short of a buck but even they saw it as back dooring because they either didn't have the brains or family connections to get in first time.
These guys don't have to pay anyone back or get a bank loan. Even after P2F if they still don't get in one said he will go to Uni in the UK and do a degree. Money no object.
These are they only guys I can see who can justify P2F
As for everone else, I don't think anyone really starts out with the intention of P2F. I see it like an addicted gambler. You pay 50/80k and no jackpot so you start chasing your losses by gambling more money instead of waiting it out or walking away.