No, you can't equate selling a landed property and selling gold, because they are off different value. Yes it's fine to sell some part of your gold to buy Bitcoin, but selling off a landed property seems unwise in my own opinion because even in our society today, their are some people that even though they are very poor, they will never sell their land for anything else, because land is of higher value in our society today than gold and Bitcoin, because it's the only asset that can't be lost for ever even though their is fire incident or any other disaster, though some people might have a different opinion but I still refuse to see it as a logical thing to do, because land are even more difficult to get in a developed area than Bitcoin and gold.
You are right not everything are supposed to be use to invest on Bitcoin but if somebody has a gold but are willing to pick Bitcoin is of course a perfect diversification because you are trying to grow from big to the bigger so first of all is to check between them who has the best potential. Meanwhile if somebody is cut to decide weather they would use their properties and exchange for Bitcoin investment and looking at the option of using the gold you have, there is no need selling anything, just use the gold instead because when you use gold is like an investor who is just changing there business and they will neither be pressured of realizing money they use for it or getting tense by anything.