2 years ago i probably would have answered this post very differently, and with much more vigor of work and move on! so it really depends on where you are in your career.
i will completely agree that quality of work environment is important, and money doesnt fix everything. i left one place as a sous chef because i was being abused and i felt a little like a whore selling my services with no quality of life at the end of the day. As a line cook you leave to move up through the ranks and eventually make it to sous chef. Young line cooks have a shelf life and there is no denying it. its just part of being young and wanting to move and push your career. i think some young guys are too concerned with constantly moving to get that first sous chef gig and they dont take time to smell the roses and line cook to their best abilities. i dont think enough cooks reach their full line cook potential before becoming sous chefs, because there is always someone out there willing to make you a sous if you leave your current employer. and too many take the bait and become sous too early.
old line cooks are different, at my current place most of us are old line cooks who have been sous chefs and are there because its a nationally recognised restaurant doing very progressive food. But people like us are few and far between. maybee not, but i have never worked in a kitchen where the average line cook age is well over 27. We all work sous chef hours, (11-15 hrs a day) we are all in charge of our stations and the ordering for those stations, and at the end we make almost sous chef money. Now im kinda an old guy, at least i feel like one, and i dont see leaving my current employer for several years. i make really good money, we are closed on sundays, my hours are better than most places in my city, and my restaurant has a little name drop to it. eventually ill have to go back to being a sous chef, and doing that dance. but its splitting hairs at this point between that and what im doing.
so i think the majority of line cooks are concerned with "moving up", getting that first sous chef job, learning and moving on, ect ect and there isnt much you can do for it. if you find a solid line cook treat them well, but not spoiled, ( thats always a pit fall too) and realise that in the end, your gonna lose that person. its just the way of the beast.