Say the house is 400,000
and you pay 20% down: 80,000
so the loan is: 320,000

if using 7%, 30 fixed, the total intersts will be about 450,000.

But at the same time, if you put the 320000 to a stock market which average 8% return, then 30 year it will become 2,900,000

But stock market has risk (also another "but" is that many people say 8% return is a kind of low estimate in the long run).

PS: we did not figure out any tax in above.