Plenty of the folks involved had degrees in other things. My take at the time (and now) was that it was a matter of good reading comprehension, good communication skills, the ability to think things through (any of a number of ways, see Polya), the ability to learn, and the ability to synthesize.

You pick a lot of that up in getting a formal education. Even one in a non-technical area (you just need to learn a bit more). It was all new. People were making it up as they went.

Edit: Also the ability to focus. As an interesting side note, when computer dating first became ‘a thing’, there was an upswing in diagnosed cases of autism. Pretty much everyone in the field was able to focus on one thing (excepting maybe Bob Frankston, who was capable of that kind of focus simultaneously on multiple things — but he came up with spreadsheets-on-PCs, not Internet protocols)