Why do people act like this?

I've been working at my current place of employment for almost two years and i generally like my coworkers but there's something i don't understand, why are they acting like they are the only ones that do anything?

I constantly hear complaints of "if i don't do it then it doesn't get done."

I work a job where team work is highly important and feel like everyone is doing a good job. We all have our individual strengths but i don't see anyone sitting on their thumbs.

The other thing i hear is "not my job." Which is the biggest road block to team work. I'm thinking a lot of them don't know the meaning of team work. We do okay but the team work aspect is lacking. I do more than my fair share but i don't complain like 99% of my coworkers.

The management also says they don't want to micromanage things but they're not managing anything or they would know what's going on with the lack of team work.

Why are people like this though? Why choose to complain all the time instead of just doing what needs to be done.

Starting to feel like my help isn't appreciated and i should go somewhere else. All this negativity is pointless and i know it's everywhere but this place is a cesspool.