I think it was because Trump is a debt guy. When you can borrow at near 0%, you do. Not saying it’s right, but it’s the way guys like Trump think.
When you can borrow at x% and use the money to make more than x%, you do. It makes sense when running a profitable business.
GOVERNMENT IS NOT A PROFITABLE BUSINESS.
It generally shouldn't be. Government debt is a heavy and usually inexcusable burden on the taxpayers.