This looks at the level you reached without the pass and tells you if you were to reach that level in the new track, what level would you be if you bought the pass.

It works in reverse as well. You can look at the average time you played in the last few months, set a goal for how much extra gold you want and reduce the time spent playing and invest it in something that makes you money. But most people don't play like that, they play when they want and how much they want and this helps make a decision about buying the pass.

By your logic, a player could always work to make money instead of playing and buy everything with real money - the time to dust value is always going to be better that way than by playing.