That's not very productive though

That comes with operational and execution risks. Selling a small chunk of your Bitcoin doesn't.

As the store of value premium on houses goes away this will not be the case anymore. Rents are inflated by parallel rising mortgage costs which are a result of boomers using them as savings instruments. Maintenance is also rising faster than house values right now. Also, being a landlord can be horrible. Custodying bitcoin is much cleaner and easier.