Because people are sheep and vastly predictable. That’s why market research works. A genpop sample of 1,000 people can predict what millions will do pretty accurately. Not going to get into detail but I’ve been in MR for decades. You can trust me on that one…
Most people will rather listen to/watch/read what millions of other people have listened to/watched/read before them, mostly so that they feel like they belong.
FOMO, laziness (no will to look for something by themselves, must be spoon-fed) and general conformism add to that. That’s how you get millions of people paying insane prices to see a decades-in-the-making perfected product like Taylor Swift on a stage, instead of looking around them and finding alternatives. Or Barbie making over $1B because “it’s the movie to watch this Summer!” or whatever. Etc. Etc.
There is is this vast misconception that popular = good. Yet so many artists that are considered incredible nowadays lived a miserable life, were dirt poor, because they were not popular in their day.