It isn't just the actors, it is the writers, directors, and especially the producers. When the shows go into syndication, they make mega dollars, and the cost is zero, just play the tapes.

The studios and the networks love the syndication; it gives them quality broadcast hours and a big audience that is pretty much guaranteed.

If a show makes it past four seasons, then it means a lot of money. Of course, the studios and the networks love it because it is like a best seller book. Just rake in the dollars. I think it is very fair that the profits are shared. And, it gives major stimulus for the show to keep it in high ratings that long.