That's a pretty problematic way of looking at things. Also, it's plainly not true.
On the one hand I have cases that make it easy for me to calculate my value. Let's say my client is being sued for 15,000€ and I make it go away, I've just 'made' him 15,000€.
But let's say that same client is now being charged with murder. He didn't do it and after trial he's declared not guilty. How much has my contribution 'made' him? Have I made him the equivalent of 30 yearly wages (30 years in prison is Belgium's max)? Or have I generated nothing at all?
And that's just being a lawyer.
Same shit goes for doctors. How much money does a doctor who performs a life saving, yet pretty standard surgery, generate?