We have no evidence whatsoever that the world will not wink out of existence tomorrow, or the day after that, or some other time in the future. Even if it doesn't, we accept that we may all die at any time, even if the chance of it is low for someone young and healthy who doesn't take many risks. Isn't it logical to live each day as if it may be our last? It would not be conducive to the running of a functional society, but nuts to that. One could argue that we must weigh the probability of death or non-existence in the near future and enjoying the present against the probability of it at a much later date and the value of planning and laying the groundwork for things to come. The problem is that it is impossible to compute these probabilities. We can attempt to guess at them, but we are very likely to underestimate the probability of death thanks to the "Black Swan" problem.