Real Estate investments only make sense when the economy functions normally. It doesn't make sense to build your portfolio upon Real Estate while the central banks are printing money out of thin air.

Real Estate are not liquid assets. In an economical crisis, you won't be able to sell them fast. Because nobody will want them. Think about it, everybody needs one house to live inside and maybe one holiday house to have fun. What you gonna do with the third one? Doesn't make any sense. Even the second house doesn't make any sense to most people. You can rent the third, but you will be just another parasite to your country's economy.

When the markets crash (they will crash eventually), your RE investments will be worthless. Everybody will be running for another country's FIAT, or most likely, it will be gold they would want to have. (Gold it is If its the USA who is having a crash)

Bitcoin also is keeping to take more air because FIAT bubble haven't burst yet. When it does, nobody will want bitcoin neither. (maybe they will, it depends on how bad the situation is)

I forgot to add: What is more dangerous than owning houses is that borrowing money from banks to own them. Owning RE itself may not harm you till everything goes fullshit but you'll get rekt easily if you owe money to the banks.