I'm not a CPA or CFP etc etc. However, my personal belief is the right balance is borrowing money when the expected rate of return is greater than the interest

I'm not a CPA or CFP etc etc. However, my personal belief is the right balance is borrowing money when the expected rate of return is greater than the interest rate on the loan. Right now money is "cheap", whether it's a mortgage, or another type of loan interest rates are about as close to 0 as they can get. There's a reason that wealthy don't call it "debt", they call it "leverage" because it can be a very useful means to an end.