Still don't see why you can't both do stuff towards your future AND enjoy yourself some in case you unexpectedly drop dead tomorrow XD
but maybe it's because there's very few things I go all or nothing on
Given that when a child is in single digits pretty much anyone in double digits is a living relic, I don't think she would feel like wifey had lied to her and not prepared her, especially if at least gets that things get old and die and sometimes get sick and die even when they're not old.
Some kids at that age will be like oh okay then and others will stress the absolute hell out about it til they either get over it or get some reassurance. I remember one of my friends' kids being really mad about the fact that they weren't going to be young forever XD
Looking in most directions that you know there might be potential danger seems like a good idea x_x