[paranorman]

The 1337 could be a nod to gamer culture because it stands for “leet” and may be popular with the folks who participate in bug bounties. Pure speculation on my part here.

EDIT: yep, looks like I missed all the other comments pointing this out, mobile app didn’t load them for some reason. Leaving the comment anyway.

[zackkitzmiller]

Just to expand on this a bit, 31337 goes waay back. Before 'gamer culture' was a thing, and was popular enough to where it got mentions in the 1995 movie Hackers.

I vividly remember BBS and IRC handles with variations of 31337 in them in the 80s. I'm sure it goes back even farther.