You could say the same for any job - you don't know what it's like until you've tried it for a while! People also pay thousands and thousands of pounds to train as doctors or lawyers, or engineers or teachers. Why not go ask them why they wanted to do it without having tried it first?
It maybe is an expensive leap of faith, but that's each prospective newbie's decision to make. What doesn't help is the old-timers yacking on and on about how 'it never happened like this before'. Times have changed - maybe just because you can't see the appeal doesn't mean that others don't, and if there's only really a limited path into the job nowadays, people will still want to do it.
Someone's got to keep the company going to pay all the airline pensions after all...