Because we've created a society where the expectation is we should all be able to do everything we want when we want regardless of circumstance. I've personally known people that would book holidays before paying their rent, then plead poverty to the local authority/landlord. OT but it's like all these folk, may of them young, you see driving £30k+ cars. Most aren't on traditional finance, they're leased, low/no deposit, not bad monthly payments etc.
Put money aside for a rainy day? Pay things that are required first? F**k that, let's SPEND!!!
disclaimer: I know many in society are genuinely living in poverty and can't book holidays, buy cars or anything. I don't need a lecture