Via gliding, via SLMG, then Group A added on, it was doable on a very modest salary, in chunks. Justification? Well, everyone needs one passion, although I suspect a passion starts as a hobby. Mine just got under the fingernails and into the bloodstream as an addiction.
Unless you can divert into a cheaper route, as per suggestions that are coming at you left, right and centre, you merely have to tell yourself, or the significant other/family/dog, that it'll all be worth it when you buy a share in something economical or a whole something that runs on 2 litres an hour and requires next to no capital outlay for years on end.
Short answer is, you can't, if you want to persuade a brain that requires justification for every pound spent on things other than a roof or food.
But if you want to inhabit a diverse society of fascinating people, mostly benign or better, discover another dimension to the hours not worked or slept and have fun like no fun has ever been, you don't need to.
