Remember...
The industry is more than just "airlines" if you want to be a working pilot.
Many 2nd career guys work in cargo because many companies are non-union, giving a person without time to climb a seniority list a chance to advance based more on merit.
Similarity corporate (most fractionals, not all have Unions) is the same way.... Same again for part 91 private owners.
Money at the TOP end of the airlines are good/great, but at the lower/middle parts, other parts surpass or match the "airlines".....so if you have less than 10 at a major, the lack of QOL, largely due to lack of seniority, might not make sense.
And a note..
Many international contracts for part 121 DO have a hard age cut off...