The law decides that. These compensations are not determined by some open "market" , but by what is basically protectionism for the legal professions in most countries. And guess who writes the laws.
> Who gets to decide how much everybody "deserves" for their work? Answer, the payer and the payee. You don't get what you deserve, you get what you negotiate.
...unless you're Musk who negotiated a deal with the company he leads only to have a few shysters insisting the deal is off while claiming 10% of the negotiated deal for themselves.
The board of Tesla did agree with the terms and conditions, probably because they thought the conditions would not be met.