She can write off car rental on her campaign. If she buys the vehicle she has to pay for it. Why spend her own money, when she can spend campaign’s money?
You’re right, of course. If one were to closely examine all of her recent campaign expenditures, it wouldn’t surprise me if she paid herself as a campaign consultant and had a few close friends and relatives on the campaign teat as well. My guess is that when she finally leaves office, all of her campaign funds are depleted.