"But Ryo-san, why won't you warn them then?"
Because I already did a couple of times before.
And every time they either don't respond at all, or block and mute me, or tell me "BUT MUH I MAST PROTECC JAPANIIZU RAWZ!!".

I already did my part, as usually nobody listens.
So once karma strikes back, I'm going to respond in the same way; ignore them, block and mute them, or tell them "you get what you fucking deserve, so enjoy the karma!".