Everyone controls their own happiness to its full extent, despite type.
If someone really wants to be happy, they can be, regardless of what bad things may have happened to them. The problem however is that many people don't want to be happy. They want to be sad. For thousands of reasons.
Quite possible, NT's have the most control over this however.
I don't agree that everyone controls their own happiness FULLY. There are people out there who experience much less anxiety and troubles phase them less than other people. It is a fact. So those people have a better chance at being happy. Now, everyone has the opportunity to make themselves happier, that's true...
Like I said, we have full control over ouyr happiness. But not everyone embraces that control, instead, most people feel the need to be sad after certain things happen. I've been there too, can totally relate. And there are people that put happiness on a pedestal that is out of their reach.
But I still think we have full control over it, should we wish it.