That is a big question, and it involves some terms that may mean different things for different people, so this can only be my personal answer. I will answer yes to the first part, because many scientists I know are happy because they do something that they enjoy, that they are good at, and that is meaningful to them. That last part is important because it will help you when at times you need to do things that by themselves you do not like doing as much but that you know will get you closer to where you want to be.

Now about rich - I know few scientists that would be called rich but there are some. I doubt that any of them started out with a goal of getting rich though. And if they did start out with that goal rather than the goal of learning more about something that they are interested in, I think they would not have made it through the long training that it takes to become a scientist.

That being said, having gone through all that training and studying to be a scientist means that you will likely end up having enough money to be comfortable. And there are studies that suggest that above a certain level of income (where you don't have to worry about "basics" any more), happiness does not increase with income.