I’ll make a more fully-featured pitch at some point, but the core is: my brain works best by connecting random different ideas together (I’m sure everyone’s does to some extent) and Obsidian lets you do that super easily. There’s also a second thing that’s almost as important which is there’s a billion community-made plugins so ANYTHING you wish Obsidian could do, someone has already built out a plugin for and all you have to do is click install (in fact this wiki is built off of obsidian too)!
This guy is a hardcore tech guy, but he also has a great video pitch for Obsidian: https://www.youtube.com/watch?v=DbsAQSIKQXk