You're a 21 year old interested in flying for a career.
You can spend 18 months having a ball at CTC in NZ etc with mates interested in the same thing as you.
Then hopefully get into EZY flying round Europe on a reasonable roster for £1,500 a month after loan repayments and then be set on your career.
Alternatively, you could plod on at your local flying club, become an FI on £500 a month teaching difficult students in aged aircraft whilst wondering whether it'll take ten years to get into a 320 or whether you'll just give up.
Alternatively you could get a spanking graduate job with Mr Big PLC or Big lawyer and be earning the same for an office job doing serious hours. PS - you still have to pay living expenses and that city wage doesn't go far in central London!
I really don't think it's that irrational choosing the CTC option, especially as people/parents have the money (which does take some getting used to).