Given reliable tenants and time, I can pay off the loan with the rent and now have all my coins and a rental property. From there, I would use the equity in the property to get another loan to purchase a new property....rinse and repeat. As far as I know, this is the safest and most reliable way to build one's wealth while also having passive income.
Rinse and repeat how many times?
I doubt that no matter what one deal in a million you will manage to find with that building you won't be covering your investment plus the interest in less than 15 years. Around here the cheapest rent is going for around 300-400 euros but you won't get any apartment for less than 80 000, those are some full 200 months of rent till ROI not even considering the damage that time will put on that house.
Of course, in your specific case the situation might be different but if it were that advantageous to rent stuff everyone would have already bought all the cheap homes, is not that you're the only one with this plan.
Now for all the bitcoin maximalist that say I wouldn't need to get a collateral loan and could just buy the property outright with btc or eth....well even if that is an option, why would I do that when I could have both? Whether it be a loan or outright selling, the risk is the same and only one strategy guarantees I'll have less crypto(selling).
Let's analyze the two scenarios, from the worst point of view.
You have 10 BTC, you sell them you get $500000, you buy your house.
You plan on getting a loan, you must come with at least 15
BTC if not 20 as collateral for the same amount, a flash crash happens, your collateral is liquidated to pay the debt.
I don't think the risk is quite the same, in one scenario you risk future gains in one you risk actual losses.