Because today women are incentivized to be so. If they were incentivized to be chaste and made marriage material, then they would follow suit. Simple as that. I wonder (((who))) is behind this development?
Women belong to all of mankind. Sealing them away and claiming exclusive rights to them is stealing from your brothers. Who was the first one who fenced off a berry bush and denied his brother's the fruit? It is far worse of a crime to deprive them of their right to take the women that they wish.