It's true that the hobby is not cheap. However the larger collections have probably been built up over very many years and the cost per year for the enjoyment that is recieved by the modeller and by others viewing the layout is also very considerable.
Many other ways to spend your money (less wisely, in MY opinion, it's just an opinion) I have not idea how much a pach of cigarettes is but I'm going to guestimate 5euro just for arguments sake, that almost Eur2,000 a year or nearly Eur18,000 over a decade. very nice layout acquired for that amount and unlikely to fall into ill health due to being run over by any model under G scale.
Diving, is equipment intensive, with consumables, boats, Nitrox, location etc.. I think trains & layouts are acquired over time depending on individual resources and level of interest, and other than causing the occasional fracas or debate on here, I think you could do much 'worse'
EDIT: As for wives, I'm pretty sure they know exactly how much most of the modellers spend and choose to turn a blind eye to it, to a greater or lesser extent. The cost of keeping you out of her kitchen, PRICELESS! (for everything else, there's Mastercard)