in cultures where men can have multiple wives don't they run out of women?

There are more women in the world than men.

that's where the rich guys have several wives and the poor guys have zero to balance it out

The ratio behind polygamy is typically that marriage is a social contract and unless women are married they will not be provided for. This can for instance make it an obligation for a man to marry his brother's widow.

They probably die in childbirth after having so many children, seriously.

Not in southern Utah..

it olny happens at Arab countires...otherwise women related to these socities will never allow their guys to avail this oppertunity

multiple......shit, I cant even find ONE woman. much less, more than one.