There's a lot of good advice. Each person has to make up their own minds. Just some opinions here from someone who knows a few cadets and someone who considers themselves pretty good with money and financially ok.
1. It is always best to be "Debt Free". Obviously, this isn't always possible. E.g. can't save for 40 years to buy a home. Most people need a mortgage. A car is definitely a necessity, but until you are debt free, a NEW $25,000+ car ISN'T.
2. Most cadets, after paying back their academy expenses and getting full pay checks, have or should have no problem graduating with around $10,000 saved up. (That's saving $416 a month for 2 years) Not saying some don't spend a lot more than others per month, but it's not difficult to have close to $10,000 saved. Especially if you had any savings to start with, such as graduation money, etc.
3. While officers don't get paid to set up a house once they graduate, you don't NEED to spend $10,000 setting up a house. I was enlisted, and when I moved into my own place, I didn't NEED to go to IKEA and Ashley's furniture to buy a lot of BRAND NEW furniture. Maybe today's generation feels they need all NEW EVERYTHING. But you don't.
4. If your existing debt, such as student loans have a significant interest rate, then it definitely makes sense to take the USAA loan at about 0.5% and use it to pay off that loan. It also makes sense to START your retirement fund now. E.g. $5,000 per year into a ROTH IRA. I also recommend once you get commissioned to start your TSP savings plan too. (Similar to a 401K).
Now; maybe because of unforeseen things, you can't graduate with $10,000 saved. Only you know what you spent your money on. There's nothing wrong with using the loan to pay off debt, but a reliable USED CAR, and invest in a ROTH IRA, some CD's, and other safe investments like Savings Bonds or similar. These won't make you rich, but they are pretty safe and you aren't locked in forever. You can always get the money back if it's an emergency. There's absolutely nothing wrong with taking the loan. Assuming, you don't do as some have done, and used it all on a new car and a graduation vacation after leaving the academy.
For what it's worth, if it wasn't already said, you start paying it back; approximately $550 a month; for the 5 years you're active duty after graduation. One thing you definitely want to ensure, is that if you take it while still at the academy, that you don't spend it until AFTER you graduate and settle in. If you leave the academy, get kicked out, or something happens that forces you out of the military before the 5 years is up, you STILL OWE THE MONEY.
Best of luck. Mike.