That.
Although I believe white supremacists to still be a fairly small percentage of the population, and perhaps not even at the highest it's been in my lifetime (hard to know for reasons I stated earlier), my concern is how much more active they are.
For me, 5 years ago, they were not of concern for two reasons. One, their numbers were falling. Two, they had shown no ingenuity in recruiting new, younger members, which meant their members were dying out with age because they simply weren't making themselves seen in places younger people were looking.
Since then, they have fixed the latter "problem," which has led to a reversal of the former trend.
That is why it's worrying to me now, despite their numbers still being small. I have seen a dramatic, obvious rise in their presence on social media and in younger circles, because now they've figured out how to reach those people.
I believe some of this is just them being more open, rather than necessarily sky-rocketing membership. But their membership IS climbing, and the fact that they are more open and promoting so broadly is in itself a concern.
I'm not going to wait until their membership is in the millions to get concerned about this. We need to be concerned now.