Is that really his decision to make?

It’s a pretty standard rule of etiquette not to tell anyone what to do with their money. You can give well-meaning advice to your friends and family when they ask for it, but offering unsolicited money advice is almost always met with backlash. It can be frustrating to watch people whom you love be completely financially irresponsible, buying cars and houses they can’t afford, and living with the stress of being one missed paycheck away from financial ruin. Unless you are their conservator, you have no control over the money moves they make. Sometimes, the only way for them to learn to be better is to reach rock bottom and figure out how to get back up. 

If you’re financially well-off, you might not feel comfortable accepting a large sum of money as a gift. If you’re making six figures and your parents, who are barely scraping by on their retirement income, offer to pay for your car, it’s only right to insist they save that money for themselves. Still, they might insist, because even though their baby is all grown up, they still want to do everything they can to support them. The parents might think it’s condescending and impolite for their kid to reject a gift just because the kid has more money than the parents. After all, it’s the parents’ money, and they should be able to do what they want with it.