Usually on YouTube, when you subscribe to a channel, you receive notifications of that
channel's activity in your YouTube feed. People wanting to grow their channels ask and beg for you to subscribe to their channel, usually at the end part of the video that everyone
skips anyway. The more
subscribers they get, the more popular their channel becomes. With all these subscribers, they grow an audience, a fan base, they become popular on YouTube. Most YouTube channels that try to achieve this never will, and the people that happen to do so eventually die having achieved nothing in real life.