It absolutely makes sense as a matter of elementary finance to use a loan when interest rates are low rather than paying cash -- I was buying a car regardless. The interest rate on the loan is far below my average rate of return investing the same amount of cash. The profit on the invested cash exceeds the loss from loan interest; I get to keep the remainder.

Similarly, I put all of my daily expenses on credit. I pay off all of that credit at the end of the month. I am still borrowing money but I am paying no interest on it.