But isn't the landlord who bought the property and is renting it out providing value by moving the property onto the rental market, so the renter can rent it and doesn't have to buy it? On the rental market, the property is accessible to more people and allows them to maintain liquidity, which can be directed into other investments (such as BTC, which may prove better in the long run).

Personally I see value in that; before I bought what is now my home, I used to rent and I'm glad there were landlords out there to make renting possible. The landlord invests a large sum of money, takes on risk etc. so others, with smaller capital, different needs (e.g. a need for greater mobility), or a different investment style can have their needs met while still having a roof over their heads.

The Austrian school teaches us that value is subjective. I'd be cautious telling others what is value and implying objectivity; that's what Marx did.