Most high stakes players and pros don't even make a living from poker alone. They all have other ways to make money or have made their money in other ways.
Anyone making a living only from poker would likely never admit it anyways for tax reasons. I mean even in
canada here where poker winnings aren't taxed, I've googled it and at a brief reading on the wording....over the long term if you have no other way of showing an income and are living just off poker. I'd bet good money the tax man will be coming for you sooner or later.
We will never know for sure but likely easily less than 5%.
Cheers!!!