When I decide to buy a $25k car because that's as much as I'm willing to spend I still need to determine what my "monthly" is. It matters what my monthly is because it is _a loan_ that I need to pay back every month. If I didn't need to think about what the monthly payment was I wouldn't need to take out a loan (unless I guess you got a magical loan that could only be paid off as a lump sum?).
You're implying "worrying about" or wanting to know what the monthly payment is on a loan is a bad thing and I don't understand why.
You're implying "worrying about" or wanting to know what the monthly payment is on a loan is a bad thing and I don't understand why.