I would love to see the details of your 600/month. Even the big 3 see less than an average of 600 a YEAR each. So at the highest average peak, 2000 pilots a year head to the big 3 and that doesn't include military, corporate, cargo etc.

Even with a liberal number of 100 guys a month at each if the big 3, that's 3600/year. Compared to your 7200/year leaving the regionals. So where are the rest going?
Jumping ship to other regionals, quitting the profession?

I don't pay too much attention but even the bigger regionals like Skywest and Expressjet lose well under 100 a month.
With numbers like you are "conservatively" posting, the regionals wouldn't have a single pilot within a few years.