Keep in mind, it's only terminally online people who agree with them all of the time. Most older adults get their information off of the news or their friends. 1.8 and 1.7 million sound like big numbers, and they are, but in terms of voter power and considering how viewership is distributed, and all of a sudden BreadTube doesn't seem so powerful anymore.
Also, a lot of those subscribers only be one issue voters, like feminists or the "I FUCKING LOVE SCIENCE" crowd. I seriously doubt that every single one of Hbomb's or Contra's viewers are all Antifa commies who want to kill every single person right of the gulag (although it is reasonable to believe there is a pipeline effect of sorts).