Its probably a carry-over thing from 4chan or sites like it, but idk for sure. And idk why 4chan and thedonald use it so much other than to be purposefully anti-politically correct.

Edit: I've heard people make statements such as, "you can be gay, just don't be a faggot". To me, this says that "faggot" is being over-the-top and annoying about it. So maybe adding -fag to the end of something is just saying they are being over the top and annoying about it? Just speculation

Its probably a carry-over thing from 4chan or sites like it, but idk for sure. And idk why 4chan and thedonald use it so much other than to be purposefully anti-politically correct