For me, learning to fly is a fulfilling a lifetimes ambition and love of aircraft. If one has to 'justify the cost', that is all the justification I need. Its an expensive hobby, but so is sailing, horseriding, skiing.....to mention but three.
I finally took the plunge when I moved jobs to an airfield and organisation with a relatively cheap Flying Club. I had waited until my mid-30s, settled, with a decent job and reasonable salary. So I understand you want to do it now, but maybe wait a few years....go through university, start your career.....then take up flying.....
Good luck whatever you decide
GQ