If you want to carry a knife, you probably should learn how to sharpen it.
If you want to drive a car, you probably should learn how to check the oil, pump gas and change a tire.
There is no definite NEED to have these skills, as there are folk who are paid to perform these services for you.
But if those folk aren't available to you at some point, then not having these skills can get real inconvenient.
This is where I'm at with it. I mean, if you think about it, very little in the modern first world is a "necessary life skill", because if you have some money in your pocket, there are no end to people who will:
- prepare food for you (restaurant)
- feed it to you (old folks home/hospice/hospital)
- pour a drink in a glass for you (restaurant)
- build a roof over your head (contractors)
- clothe you (old folks home/hospice/hospital)
- bathe you (old folks home/hospice/hospital)
- transport you somewhere (Lyft/Uber)
- Grocery shop for you (Online grocery delivery services)
And so on. I know an awful lot of well paid people who are absolutely worthless and who can't (or don't) do anything for themselves. Maybe a hundred years ago, it would have been considered a necessary life skill, because we didn't live in a country that's 90% service industry like we do now.
All that said, I think sharpening a knife now falls in the column of "Lifeskills it's great to know if you want to be considered self-sufficient." I think self suffiency is an excellent goal to work towards.