I disagree with your last point. If enough people get another job, the industry they are leaving will adapt or die. Since people still want to be distracted from life (big demand) the industry will more likely adapt.
The point is, people don't want the dying option here. That's why they stay.
That's essentially a union. A large group of people say they'll leave unless things improve.
The only way that happens is with a union. The union is what lets the workers organize for the kind of collective action that forces an industry to adapt.