It's what if, not a certainty. Most of the decisions rely heavily on the certainty of living tomorrow. Which can be highly probable, but not 100% certain. So, that makes it possible to reconsider some decisions.

Like, should I pay for this expensive dinner or travel, or should I save the money? Sometimes saving the money makes sense, sometimes it does not. But you should never rely on the fact that you will be there to use the money you're saving instead of enjoying a nice experience right there.