Sure, a black market is possible - I explicitly mentioned legitimate sellers.
But why would you want to sell a house this way instead for a permitted means of payment? Even if your scheme is unlikely to be detected, if does add a nontrivial risk of getting detected (or getting intentionally exposed, or blackmailed to get exposed) and get very unpleasant consequences for that, and given the extra difficulties of enforcing the deal, you would likely expect a significant extra markup above "normal price" to sell the house this way. Furthermore, if this is criminalized, then even offering or requesting this as an option carries some risk.
Also, I'm not informed of Indian law, but in most western countries this "donation of house" would definitely incur a significant tax and possibly trigger a tax audit/money laundering investigation. Combined with the risk markup, that would meant that laundering cryptocurrencies would be somewhat expensive. Not impossible, of course, money gets laundered - but it would mean that you would actually have to follow all the inconveniences, risks and costs of a money laundering process if you'd want to handle cryptocurrency, and that would discourage many people from doing so.
> But why would you want to sell a house this way instead for a permitted means of payment?
I can think of a few reasons. The buyer offers you a large premium, you know people who can help you offload the currency, you have no interest in keeping your capital in a controlled environment, maybe you're selling your house because you're leaving a country and taking bitcoin or whatever is the easiest way to take your capital with you.
But why would you want to sell a house this way instead for a permitted means of payment? Even if your scheme is unlikely to be detected, if does add a nontrivial risk of getting detected (or getting intentionally exposed, or blackmailed to get exposed) and get very unpleasant consequences for that, and given the extra difficulties of enforcing the deal, you would likely expect a significant extra markup above "normal price" to sell the house this way. Furthermore, if this is criminalized, then even offering or requesting this as an option carries some risk.
Also, I'm not informed of Indian law, but in most western countries this "donation of house" would definitely incur a significant tax and possibly trigger a tax audit/money laundering investigation. Combined with the risk markup, that would meant that laundering cryptocurrencies would be somewhat expensive. Not impossible, of course, money gets laundered - but it would mean that you would actually have to follow all the inconveniences, risks and costs of a money laundering process if you'd want to handle cryptocurrency, and that would discourage many people from doing so.