I agree in principle with what WWW says. We would all love to be in the position that you propose, whereby you work hard and save up for the training costs. Your points are prudent ones but unfortunately some of us do not have the luxury to make your suggested choices.
Take me as an example. I can't move in with my parents because (and not wanting to be dramatic) they're dead. So I can't save money by living in cheaper digs.
On the point of working balls-out in three jobs: well, I left my bank job without anything else to go to simply because I hated it that much. I simply could not stand being there and it got to the point that I didn't want to wake up in the mornings for work.
Sure, few people really get excited about work to the point that they leap out of bed on a Monday morning. Even astronauts and parachute instructors have their off days. But I was in an extremely crap working life and I saw others around me get sucked so far into their despised careers that they didn't dare leave. It's hard to leave when there's a cushy pension and easy hours. Things get too comfortable and secure. You get your wages, you work a few hours but then, at the end of it, you can just go home and switch off.
I realise fully how expensive a debt this is. I am also aware that it will no doubt cripple me financially when I do end up working as an instructor for a decade. But even the unpleasant thought of knowing that I'll be relying on a beloved partner for help is a thousand times better than the thought of going back to where I came from.
I've been flying as a PPL for enough years to want this lifestyle badly. At a glance, my decision to borrow so much money may seem blase and rash. But I hope you'll appreciate that an awful lot of thought has been put into it.
Ratpup