And what they do all day?
I have my flame-proof hard-hat ready 
In the spirit of the general shit-stirring on here today I though I would ask this - as I do really wonder. Fair enough when you have pre-school aged children, I can understand wanting to be a SAHM. But once your children are at school full-time, what is there to do all day?
I work PT (school hours, basically). I manage (jointly with DH) to get all the housework, cooking, diy, etc) done in the evenings & weekends, no problem. If I were at home all day I really think I would go a bit mad - either that or I fear I would gradually become relegated to the role of house-slave, doing all the housework and childcare myself because I wouldn't have the excuse of a 'proper' job. . .