simple, the day you have to justify it means you can no longer afford to do it.

i get lectured at work daily about spending on my cars, i put it down to that fact i'm the only one there not already being measured up for my wooden long term sleeping box.

"why don't you save for a house" simple, i can get a 60k mortgage wich still leaves me 60k short of the price of a house that i'd actually want to live in, even if i save every penny i earn for the next 4 years i still couldnt afford a house and would be bloody miserable in the mean time!

"why don't you put the money away and let it earn for you" why?! i die tomorrow my folks then have the hassle of getting it back off the banks and i've worked bloody hard then to pay for my parents holiday?! i think not!!

end of the day you do it because you enjoy it, the day you stop enjoying it stop spending on it.