A lot of people don't give rap a chance because they don't like the things rap is associated with, alongside a hatred for the mainstream. Rap isn't something you can really just blow off though, because rap is incredible. It's poetry with rhythm.
I personally enjoy rap. It's not something I'll listen to every day, but it isn't something I can get sick of. If you really think you hate it, then that's fine by me - everybody is entitled to their own opinion. However, if you are going to say something such as "all rap is bad", I am going to blow off your opinion as one that is uneducated or without experience. There's something for everyone, and as easy as it is to say, you have to search to find something you might like.
Give rap a trash, because rap is a good genre.