Gross pay (not including employee benefits and before payroll tax deduction), split among a team of 5 people, unclear if they were working on this one project full time, and amortized over other months with less renumeration. It may not be better amortized pay than a regular software job.
Especially considering that the authors are some of the best bug bounty hunters in the world. $500 an hour is a fairly normal rate for a top security consultant, as far as I'm aware.
https://twitter.com/samwcyo/status/1314310787243167744