Most people "chase" happiness.
And, most people are addicted to happiness like a drug.
For anyone who is on Facebook, here's an example...I'm sure we've all seen it.
Girl or guy posts to their significant other "I love you so much, you are everything to me, blah blah blah". Then a week later, or a day later, you see their relationship status changed to "single".
So what happened?
In most cases, at least one of them is chasing happiness. So they'll move on to someone else, and eventually repeat the same example above, and it will continue over, and over, and over again until they learn that you can't chase happiness (some people never learn).
Now, this isn't just with relationships...for some people it's cars, others it's boats, houses, vacations, etc... These things are all like drugs, and eventually what you have just isn't enough, you need more. The minute you aren't happy, you go looking for your next fix.
And, when you look at how people are saturated (from birth) with marketing from every product under the sun, things you supposedly need to be happy....I see exactly why it happens. People want more, more, more and this attitude of "I must always be super happy" invades all areas of life.
I'm reminded of the story of the company that moved their product manufacturing offshore, and hired tribe members as workers. After they got their first paycheck, no one showed up to work the next week. So, company officials go to see what the problem is, and they are told that they don't need to work, because they have everything they need and want . . . why work? Well, the plant couldn't just sit idle, they had to figure this out. Someone at the company had the idea to send everyone in the tribe a mail order catalog . . . they all reported to work the next week. Now, I don't know if that's true or not, but regardless, the lesson behind it holds true.
Happiness is a result of living life the way you should and being content in your situation. It's a by-product, you can't "chase" it. Sure, you can get temporary happiness by chasing it...but never true long term happiness.