Most people writing VBA code for excel are only informal programmers. For example, I never took a CS course in my life but learned VBA and programming on the job. Since then I've learned python and other languages but when I'm doing a home project or something I always come back to python. It's just so easy. I was working on a macro the other day in Excel, it took me a couple hours to get it all working but I'm pretty confident that if I could've coded in python I could've banged it out in 20 minutes or less.

Edit: I suppose my point got a little lost. What I mean is that I highly doubt much Excel code is a "big project." It may feel that way when you crawl through some of the hideous VBA coding I've done but much of this is due to the inexperience of the coder and the realities of VBA. Give me python + 4 or 5 libraries and I could recode anything I've ever made in VBA in 1000 lines or less.