That some people buy them and don't really need them has zero relevance on whether any people have need for them.

How people use the vehicles that they buy is pretty well understood from the market research done by the car industry. In the US, the widespread use of pickup trucks a passenger vehicles is a known fact.

An odd thing is that my family visited a rural part of England last year, and we saw very few pickup trucks on the roads and in the towns. On a walking tour, you see a lot of farms up close because the paths go through farms and along fence lines. The farms had utility vehicles including light trucks, but they also had regular passenger cars.

And a lot of people have occasional need for a truck but don't want to or can't afford to own more than one car, so they use the truck for all their driving.