It's really hard to say that someone should not have their kids. I only have two and if you look at our financial situation, one could say that we have too many based on that alone. When I was working full time before I lost my job, we had more than enough to support the kids, but is money really worth it when my children are ten times happier to have me home more? Isn't it better for them to be happy and healthy than stuff and nice clothes? Therefore, Specialk3749, as long as the kids are happy and properly taken care of, who cares?
If people are having lots of kids merely for attention, then it's too much and they need to reconsider. If someone wants a child merely for the tax break (and I do know of someone who said they wanted a child for that reason alone), then they should not have children. Children should be seen as and treated like the blessing they are, and if someone can not give their child(ren) the love and attention they need, no matter how many they have, then it's too many.
I know of a woman who can't handle her one child because she's too selfish and wrapped up in having men pay attention to her than properly taking care of her daughter. She has too many kids (but I adore that little girl and miss her terribly!). I also have a friend who had to use help just to get pregnant with her son and when they wanted one more, got triplets. She adores them all and they are beautiful, well taken care of, and happy. She does not have too many kids. There are just too many factors and every person/situation is different.