It's simple math/microeconomics. Every species on Earth attempts to maximize his or her resources according to perceived probabilities. When a pilot with a wet ATP gets a call from Mesa, whether they know it or not, their brain considers the following:

(Perceived years of service as FO x average FO payrate for those years)

+

(Perceived years of service as CA x average CA payrate for those years)

+

(Perceived probability of achieving legacy/dream job x perceived liftetime earnings at that job after # of years at Mesa)

+

Normative/non-quantitative factors such as domiciles, SJS, and short-term incentives such as ease of interview process, training in PHX instead of somewhere terrible, etc..

The reason we are filling classes is obvious and very, very simple if you view it cynically from the perspective of a behavioral economist--we are still filling classes b/c the above equation results in a picture that seems rosier to our new hires relative to the picture they see at other regionals/flying jobs.

On the other hand, when higher-paying regionals vote down concessionary contracts, the same principles apply--a majority of pilots on property are simply acting in their best interests: a majority of pilots on property have decided they'd rather take the odds of losing their job (at their seniority level), rather than take a paycut.

We can sit here and try to explain our career decisions in emotional/moral terms, and fight each other rhetorically all day long, but it's all just simple math at the end of the day, and we're just trying to apply words/meaning to something that's all just cold hard subconscious logic.