^^^If you got 10 Million dollars with no assured way of making a penny more, IMO, you shouldn't be investing $3M in a house period. $1.5M top and BUY IT. But say you want a $3M house, just BUY IT. What difference will it make if you're making payments? That just means if you do finally pay it off after 10-30 years, you've paid $4M(after interest)for your $3M house. If you opt to quit making payments, you get foreclosed, lawsuits from lenders, ect.
Even if you buy the $3M house when you can afford it, and have to resell it someday for $2M to get rid of it reasl quick you're still coming out $2M richer in the end and in a better situation than 1 day being broke with no paid off home, right?
I bought my home cash for that exact reason. It's crazy to not have overhead like Mortgage/Rent. That's what most people work to pay. I'd rather have $7M in the bank and never have to pay mortgage/rent again than to have $9.5M with a $30k a month mortgage. God forbid I opt not to make a payment in year 8 or 9 of paying on that 10 year mortgage and have nothing to show for the $30k a month I shelled out the last 8-9 years, it happens all the time.