Let's pretend I hire two people: The first is a private detective, the other is an entertainer.
The private detective is able to follow you around and watch everything you do. They know when you eat, when you sleep, and even when you poop. They know who you talk to and for how long. They know everything that interests you and bores you, down to the microsecond (knowing what makes you pause). The PI gets to know you pretty well and honestly, probably better than many close friends.
The entertainer is your main source of entertainment. They offer a wide variety of things and they're highly addictive and prevent you from being bored. Since they are a major part of your day, they are a major influence of the information that you consume. Be this in comedy, politics, academic information, or whatever. That all depends on what interests you that day.
Now I've hired these two people and am able to direct them. The PI are my eyes and ears, the entertainer are my hands. If I want to make the most profit off of you I can make deals with McDonalds and get the entertainer to influence you that way (maybe do comedy bits about burgers) and the PI can track how interested and influential the entertainer is. Allowing us to refine our techniques on a personal level. On the other hand, if I am interested in politics I can do the same. I know what makes you afraid. I know what makes you sad. I know what makes you angry. I know what makes you feel good.
Now we're just looking at you, a single person here. But I have a billion PIs and entertainers. I know all your friends, family members, and even your crushes. I know how close all these bonds are because I'm doing to them what I am doing to you. Consider this and then tell me that I don't have influence over you. I am a significant part of your environment. You may have free will, but you are also a product of your environment.
> My naive assumption is that Tiktok is a meme sharing platform and timesink
And that's why I have influence over you. The less important you think it is, the more influence I have since your guard is down. Same way comedians crack people up.