Waiting for sex

Why do people wait to have sex until they are married? I think it's stupid because most virgins think they are suddenly in love with the other person even if it was just a one night stand. PLUS do you really want to be with someone you aren't sexually compatible with? The first time generally is awkward right? So why not get it over with and find out if u r compatible now. Most people who aren't sexually compatible don't last. So it's better to break up instead of get a divorce.