Student here who used the GI Bill.

In addition to paying for the tuition for the class and a book stipend, Uncle Sam also pays about $1600-$2100 per month in "Basic Allowance for Housing," depending on the cost of living in the local area.

Veterans who ain't the book-learnin' type will enroll in classes just to get the BAH. They won't pass, but they still pocket that monthly check, which is significant (especially just after getting out of the military). I like to tell said vets that it's a lot neater to get at least some college credit out of the deal, but it is what it is.

Note that withdrawing from the class means that you have to pay the tuition back, so this will also baffle professors wondering why they don't drop the class.