How? I really don't understand people sometimes..

I have this constant problem of reading people's comments on youtube, and other sites.
Saying how K-Pop is gay and making false accusations and rude comments.
And then they go about idolizing their music that they call 'the best'.
Why can't they just deal with that not everybody is the same and that it is okay to like different things?!

So I ignore their mean comments, hoping that they will go away.. 
But it only turns out worse and worse until fans actually start believeing them and end up switching over in the end..

I seriously don't understand.. -____-"