I'm going to stop you there because right here is where I think you are incorrect. It is not "growing", it has been here for years and years. They just were not this vocal, and less organized and fractured. But the ideology was still carried quietly by a lot of people. Now thanks to the collective of the internet, and the anonymity it provided these people were able to really speak how they felt. And when they all saw how many like minded individuals there were, they eventually became more emboldened.
So no, I don't think it is "growing". Unless by "growing" you really mean that they have become more vocal and re-organizing. Then yes, their noise is growing after spending a long time quietly mumbling among themselves. The people who already felt this way are just not afraid to let it out when they are gathered together. Individually they'll keep quiet but now the internet has given them a sense of unity.
Disagree with me if you will, but it's of my personal opinion the catalyst for them to really get pissed off was the election of a black man to office. Something that for most of them was completely and utterly unthinkable. And the road of the last eight years brought them here. People like Steve Bannon knew they were there, and knew the powder keg to really light a fire under there ass was there. Someone just needed to deliver a message that would give them the final rallying to largely unite.
So I wish people would stop pretending like they didn't exist before 2017.