Question for the Women: Why do women like bad boys?

I am wondering why girls/women like the bad boy types who do the worst stuff; {sleep with them then leave; have other gfs; use them for their money; are abusive emtionally or physically; etc., etc., etc.} And still stay or go back to them? And guys who are dependable, (real men) get the 'just friends' crap? This has been happening to me as long as I can remember and frankly I'm sick of it. Any advice would be appricated.