I don't think the formula is particularly linear. Double value produced means double the salary is likely the wrong equation, but it is right in principle.
If you work hard you will be developing a lot more relevant skills than floating along. This makes you more valuable. Not everyone recognizes, or is willing to pay for that extra value in salary or promotions. But some people will, and some people are.
In the event you strike out on your own as a freelancer or your own business, working in that manner becomes your lifeblood that will make or break you.
I get more reward and fulfillment from my hobbies and personal relationships than I'll ever get from creating another CRUD app for ${boring_business}. Half effort leaves me more energy for those things, and half effort still gives me more than enough experience and talking points to nail my next interview and demonstrate value to hiring managers.
> In the event you strike out on your own as a freelancer or your own business
I have no intentions to do this, but if I ever did, then as my own boss my performance would be directly tied to what I earn. So yes, I'd have a much different approach.
Edit: if I could double my output and know that my salary would double too, I'd do it in a heartbeat. But I've never found a company with a comp structure that can actually achieve that. It's far more effective to just go on autopilot for a year or two, then get a 30% raise at a new job. Rinse and repeat.