good trade off. My current annual interest is approx $9500. $360k invested earns an average return of 10% per year, which is $36,000. So yeah that is a deal I make all day long. Even If I only invested the $360k in "safe" investments like treasuries I could still earn $15k per year in interest. So it would still be a good trade. Also when itemizing deductions on my taxes I get to deduct the mortgage interest. So my true "interest expense" is closer to $6k per year.