I did GSoC over a decade ago (Wow!) and if the stipend was halfed I wouldn't have bothered -- any bottom of the barrel internship would've been more lucrative.

Not that the money was the primary driver for GSoC, but being able to dedicate a significant chunk of my summer to a project while being being able to pay the bills was a prerequisite for applying.

I have no idea how I'd juggle a GSoC project with another job, for that matter.