Should I buy a grand prix even though Pontiac is gone?

Ok so I found a 2002 Pontiac grand prix gt for sale at a big dealership that has new and used cars for sale. They were asking $5,987 and I got them down to $5,000 cash out the door including tax, tag, title, etc. It's a great car! It has leather, sunroof, heads up display, power and heated driver seat, almost brand new tires, steering wheel controls, on-star equipped, and the headlights are clear, not foggy and cracked and in bad shape, Bose sound system, etc. It's a one owner car they got it on a trade in. Clean carfax. It does have 154,000 miles on it but it's in great condition! My dad (who by the way is not paying for it) says I shouldn't buy it because they don't make Pontiac anymore and they dont make Pontiac parts any more and that I should not buy a Pontiac or oldsmobile. And he was saying all these 'what if' senerios and that I couldnt fix it because they don't make Pontiac parts anymore. Is this true? Should I not buy this awsome car?