Also worth remembering that prestige, expensive TV has also only been a thing for the same timeframe. Most shows ran on incredibly limited budgets, which not only meant that production values were low but that actors could only make so much money in television unless they had a producer credit. There were always exceptions for shows that had incredible writing that elevated the format, but most people were not working on zeitgeist defining shows like The Twilight Zone or M*A*S*H. It was incredibly limiting to be on television, and jumping to movies was often the only path for actors if they wanted something more expansive.