Any and all retention issues that 91 & 135 biz jet operators are having is 100% their own fault.
Most have had their collective heads in the sand, allowing good people to vote with their feet, for years.
Most departments (pricipals and "leadership" alike) have just flat-out refused to listen to the needs of their flight crews, as far as compensation, schedule, QoL, etc.

If they're struggling, they've earned it.