The User List is anything but random. It can be arranged by the last time the user logged on, alphabetically, or several other criteria. The default display is by number of posts, largest number first.
The title at the top of each column is a link to rearrange by that criteria. The active arrangement has a tiny triangle next to the title at the top of the column. You can click on the triangle to flip the list upsidedown, or from A-Z to Z-A.
You may also click on a letter in the box at the top to see only names starting with that letter. Then you can arrange them by clicking on one of the column titles. You may also search for a name or partial name with the search box.
I'll go into more depth about the User List in a post later just about that. Only registered members who are logged in can see the User List.