Why is sex seen as a bad thing?

It is considered a private thing to talk about. 

America was originally colonized by Puritans

. They thought anything that felt good was pure evil. And they would enforce that belief on everyone else in their society. 

Because many people still cherish sex with the one they love and those people feel it's a very private thing.  Talking about sex can also lead to you getting in trouble for sexual harassment or assault.  It's also low class and tacky, like talking about how much money you have or what your bowel movement was like.  

Most people aren’t as mature as you are. Talking about something like that makes them all nervous and giggly. Embarrassed even. But It’s hard to imagine anything more basic than the human sexual drive. You can be half dead and still have that part of you functioning pretty efficiently. So it’s obviously something that’s at the core of the human experience. Otherwise humanity would have died out long ago.

Most people aren’t as mature as you are. Talking about something like that makes them all nervous and giggly. Embarrassed even. But It’s hard to imagine anything more basic than the human sexual drive. You can be half dead and still have that part of you functioning pretty efficiently. So it’s obviously something that’s at the core of the human experience. Otherwise humanity would have died out long ago.

maybe because jesus never had a female .. think about it , the aposyles where all men ..and not 1 mention of a girl friend or woman ..

Sex is seen as bad by old prudes that are jealous to see young pretty women get it.

cause not everyone gets to do it

Too many substance abusers and stupid people. 

It is Human beings are immature,  selfish, and idiotic in  general. When you add sex to it  people  make things worse and in turn makes  everything worse.