No it isn't. Wealthy people just have more options for staving of misery, which isn't the same thing as being happy.

I am friends with a few super-wealthy people, one who had access to great wealth through business and another who's a prominent aristocrat. When I say friends, I don't mean that we hang out to drink champagne, but that I'm privy to intimate details of their family/personal lives. Wealth does not inoculate you against crippling emotional problems.