You say you’re a consultant and yet link to a definition of a sole contractor.

Again, I’m talking about consulting, not contracting. Those are different. If you don’t know the difference then here’s a definition of a consultant https://www.lawinsider.com/dictionary/consultant

Now, to a layman, these may look identical. To a consultant, these are vastly different things.

You are not paid on output, you are paid on outcome.

You're misunderstanding me. I'm saying it is extremely rare for a consultant to earn multiple millions a year. On the cases it is possible, they are going to be very niche individuals not going into a company via Deloitte etc but as themselves.