Deja Vu-
Isn’t this what people did during the last bubble, they bought a house,took out a second/HELOC used that to put down on another house then rinse and repeat. The only thing is you need to do this from the beginning of the housing appreciation period and you need to sell before the crash. Good luck! If you are however trying to pay for 1 house that you will live in then I don’t think you can buy a $250k mortgage (after applying $150k) and only pay $1000/mo.