It really depends on the person. (I think)
Everything is a game, even life. Having a career, being highly successful and acquiring a lot of money are also games. The better you get at it the more you'll have to compete to get even better. Rich people hang out mostly with rich people. And poor people with poor people. Ever noticed that? :D
There's also a clear mindset difference. Rich people (those who worked their way up) are highly disciplined in their work, fully committed. I couldn't do that. They don't focus nearly as much on their weaknesses, but mostly on their strengths. They have a innate drive that makes them the first to get up in the morning the last to go home from work.

I used to think "damn rich people" at for some time, but the truth is I wouldn't succeed in being rich and successful in the way they are. I'm not like those people.

And I'm also no genius. I wouldn't get rich by inventing something either :P

I'm a normal bloke. And normal blokes don't get rich. For me simply "being" is tough enough.

But we are all affected by a competition. Whether it's our looks, our manners, our skills or the riches we acquire. The game never ends.
We can choose to not play it it, but it will still make us want more if we see the next person driving a porsche to work while you tell yourself you are happy with your bicycle.

That's how I see it :D

At an individual level it's tied to moods, yes. Getting new stuff usually makes us happy. If your life in general isn't happy - you aren't happy with your life - you start doing the things that make you happy the easiest: eating, shopping, drinking, cursing others for their happiness. Getting happy requires usually a lot of work - self-development mostly. Unhappy people might not even think about it that everything they feel starts from their thoughts and actions. You are the master of your own happiness!

And that's how I see that :D