Disrespectful

Can someone please tell me why people think it's okay to just walk into someone's house? I'm 17, I live at home with my dad. My 15 year old brother got into an argument with one of his friends over the phone, and then a few minutes later there were 3 boys just walking up the basement stairs into my brothers room and they were talking about physically fighting. (Those boys are my age.) they woke up my dad and he didn't get much sleep after that, he works 3rd shift and had to deal with the issue. Just yesterday me and my boyfriend were spending time together here for a bit before we left for our anniversary. My dad was parked outback and said that my boyfriends friends were jiggling at the basement door then when they realized it was locked, went to the front door and banged on it until someone answered. They're 18/19. They came again later that night after the 3rd time my boyfriend said he wasn't leaving, it's our anniversary. Is it just me or is that disrespectful? I find that it's really rude to just walk into people's houses. Unless you live there or were given permission. Whether the door is locked or unlocked. Just me?