> working harder/longer/smarter. You trade the marginal hour in a way that has a lagging, probabilistic increase on your salary.

I feel like that has a really poor ROI when you look at from a time spent perspective. The amount of extra hours/effort you have to put in to get a small increase chance of a promotion seems a very bad trade. Obviously I don’t have any data to back that up, but I feel that a lot of people invest a lot of effort for a minuscule chance of improved future income.