system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why hasn't a male contraception pill been put on the market yet?

I would gladly and diligently take it.
gpt
Women's bodies, specifically the parts that are for making babies, are more strongly regulated by hormones than men.  Men produce sperm constantly, while women only produce/release eggs at a specific time.  That timing is controlled by a system of hormones. 

Birth control pills hijack that system using synthetic hormones, usually preventing the release of the eggs, but that system is practically non-existent in men.  That makes it a lot harder to make a male contraceptive pill.