Sometimes it's better than the alternative. If I only need a thing once and I likely won't ever need it again (e.g. a chainsaw when I cut down trees in my backyard a few years ago), I'm willing to make the trade-off. If I bought it instead, I'd still sell for half price and need to spend the time selling it. It's a wash either way, so I'll do the easier thing.

I'll buy other things that I'll use occasionally. For example, I own an angle grinder, which I've used a handful of times. If it was cheaper to rent, I would. But home improvement stores are in the business of selling tools, so they want to increase rent enough that people will lean toward buying instead of renting.