Maybe extrovert people just don't want to admit they're unhappy, because there's such a high social pressure to be happy all the time - people don't want to spend time with unhappy people, so everyone pretends they're happy. Introverts on the other hand just don't care :)
I tend to agree with you. I find that certain people I know who are extroverts always seem happy, but you spend enough time with them and get to know them, it's more or less a facade and they're not any more or less happy than others. Just like anything else I don't believe this to be universal, but it may be more common than advertised.
