Honestly, I sometime wonder how hard it is to blow a bunch of money.
I'm a trust fund kid, and so are both of my brothers. My one brother is frugal like me, but the other is not in any way. He works, but he has bought all kinds of expensive things -- like a $500,000 house, and $65,000 corvette, and he goes out to the bars and spends $100+ probably 4 days a week. He also goes on 2-week vacations probably 4 times a year. He is 38 now, and he's been living like this since he was 18. He never worked hard in HS or college (C student). Yet, he inherited a building worth $1.2 million, and this building's tenant is a bank that sends him a monthly check totalling $60,000/year. It'd be really hard for him to screw this up. He would have to sell the building to really screw up, and I just don't see that happening. He works, and he makes about $80k/year in real estate -- the field my dad made all of his money in and set him up -- but he doesn't save really at all. He doesn't really need to. His house is completely paid off from money he inherited, he has his retirement funded in the form of this building and 2 other rental properties he inherited. He's pretty much set.
So, I think it's actually pretty tough to blow millions of dollars, unless you go out and buy ferraris or blow a mil in Vegas in one weekend or something so stupid it's hard to imagine anyone from an upper-middle-class or above family doing.
Anyway, that's just my opinion. I, personally, act like the money isn't there. It's a strain on friendships. People don't like those who show off wealth. I drive a Ford Fusion (new but it isn't a Vet), and I never touch the money I inherited.
I also want to really emphasize the strain on friendships part. Most of your child's friends will not be in this situation. They will resent it if your son has no debt and can go out to the bars every night in college. They will resent it after college when he doesn't have car payments and student loans. His GFs will resent it (or try to take him) when they feel they've worked as hard as him, but they weren't dealt the cards he was. If he owns property at a young age, the people who work in the office will resent him in some ways. His tenants will resent paying money to a young owner. Although it's a nice problem to have, it can make you a bit of a pariah when people struggle and you aren't, just because of who your parents/grandparents are. I don't flaunt my wealth, but I often feel bad interacting with people who are smarter/harder-working than me, and yet I could probably retire today, while they're $100,000 in student loan debt (my fellow graduate students). I can't offer to buy them lunch, because then they start asking where my extra money comes from. So, just keep this in mind.