Happiness is definitely a skill. Happiness is an emotion and we all have control of our own emotions (even though it doesn't always seem like we do).
In fact, I have written a hub about what influences our emotions.
Check it out: http://hubpages.com/health/Notes-Get-the-Edge-by-T...
There are also other factors that can affect our emotions, which I will put up in my later hubs. Here's a sneak peak though:
Our "rules" on how life should be - when do I allow myself to feel happy? Or what makes you feel happy? Everyone has their own unique rules about how life should be.
Perhaps this person, who seemingly has everything, has rules that are too stringent to feel happy. For example, in order to feel happy, I need to earn $5 million/yr, but this year, I only earned $4 million.
Or maybe happiness is not linked to anything that person already has. For example, a person may link happiness to just lying on the beach one day out of the week. But this person is so successful in business/family life/health that he has no time for himself.
There are many more reasons for why we have certain emotions and how to get out of them.
In fact, if you become a follower of my hubs, you will be able to read a hub about "How to get rid of negative emotions" in the next 3 days.
Again, check out what influence our emotions: http://hubpages.com/health/Notes-Get-the-Edge-by-T...