What you are describing here, to me, sounds more like contentment than happiness. Maybe I am just splitting hairs but I think there is an important distinction. To be content is not necessarily the same as being happy, although I think many people believe this to be the case.

Being happy is not wrong. One does not have to "sell out," so to speak, to be happy, I think. Being happy is no different than being sad, angry, hopeless, joyful, or any other feeling; it is a momentary state that does not last forever.

Contentment, or "being at peace," however, is an entirely different thing, in my opinion. I do not see contentment as an emotion but as a state of being one is striving for. This is more of what you are describing I think, where a person settles (for better or for worse) that life is as good as it will get and that the bad things are not so bad as to be constantly grappling and struggling with them. Contentment comes at a cost, like you said, of that "drive," that struggle that makes humanity so... human. But I think life is also tiring, and it is perhaps equally understandable to want some kind of rest from the constant conflict.