Not all investments are positive sum - metals are zero sum, proof of work coins are negative sum.

You can’t build a building on top of nothing so if land has a building on it you can apportion some of the productivity of the building to the land itself.

Agreed land without improvements is zero sum.

I didn't mean for society, I really meant for the investors, and investor in real estate has the option to rent it out so buyers of real estate operate a positive sum business.

I'm not talking about zero sum to society. I mean to investors. Land isn't zero sum because you can rent it out.

By that definition you can lend your crypto as well making it positive sum.

When you lend your crypto you're transferring ownership, when you rent you aren't. So crypto loans only make money through interest while land makes rent well over interest.