Time and effort to sell is also cost

Yeah if I see a “used once” tool on Craigslist, I’m not paying 95% of retail for it

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.

He said the exact opposite.

Seems like renting with extra risk and steps

You do not understand that capitalism and markets are not the best solution for everyone, do you?