The current situation: Unless you're super-rich, managing your money is hard. And if you are super-rich, presumably you're only really managing it in the same way that a hose-pipe connected to an ocean sea manages water, so no great boast for you there. No, the fact is that with a finite amount of money every month and a highly flexible, not-always-convenient list of potential expenses to cover out of that, things don't always add up. But they do often subtract. Between having somewhere to live, being able to feed and clothe oneself, and actually having a life and having fun, budgeting is often a task that people have serious trouble with, particularly if they're not terribly disciplined when it comes to asserting the correct savings/shiny things ratio.
If everyone thought like a gamer: Everyone would be ultra-thrifty. Seriously. No-one is more disciplined with their cash than a gamer (within a game world, anyway). Following the standard RPG-player behaviour pattern, purchases of any kind would be made rarely, and only after a very stringent, lengthy appraisal conducted to ensure that the considered item really is enough of an upgrade over the stuff the buyer already owns. And no-one would ever own more than one version of any particular thing at a time.
Thinking of buying a new pair of shoes? Will the pair you're looking at really make you run a great deal faster than your current one? Is the coat you're looking at really significantly warmer than the one you own now? Not just by one or two Warmth Points, but by at least 10? With a strict one in, one out policy on all purchases, hours of stringent in-store comparison before even considering a buy, not to mention the inherent obsessive-compulsive collection and hoarding of every bit of money ever spotted anywhere, right down to the tiniest denominations of coinage (and regardless of whether there’s physically room in the wallet or not), people would live fairly Spartan lives, but would have stacks of spare cash in case of emergencies.
And that's before you even consider the fact that no-one would even bother buying food or booking a hotel unless it was a life-or-death situation.