Why do we cry on Tisha B'av?

if you tell people listen I don't feel bad the BET mikdash was destroyed they're going to tell you listen there's something wrong with you you should change now the response is when you show up to the and you're sitting on the floor like everybody else what's everybody doing well they're looking at the book but in reality what's everybody doing they're always looking at the three guys that are crying say why is he crying why is he crying well it's his house why he lived there why his uncle owned it built it what happened because once we understood the significance of the bet mikdash you'd actually cry every day a little bit every day little bit every single day of why we don't have the bet mdash