Note that the ACTUAL organizer of the treasure hunt is not Michel Becker, but Régis Hauser (aka Max Valentin) who died more than 10 years ago.
Michel Becker only helped illustrate the book that is the support for the hunt and has taken over it when he passed.
As far as I know this was quite controversial because he had not knowledge about the riddles or how to solve them, and was only able to take over because there was a notarized enveloped left behind by the original creator which explained everything.
Could you explain more because the author passed away and left the solutions to the riddles in a notarised envelope to a close collaborator who worked on another part of the book so the hunt could live on - the solution is finally found by an unrelated party a whole decade later - doesn’t seem notably controversial to me?
There are more details on the french wikipedia article but basically Michel Becker did everything he could to make money out of the success of the treasure hunt, doing things that were either unethical or deemed contrary to the true creator's original intent.
This included taking possession of the solution which wasn't meant for him to get, trying to sell the prize for himself and releasing new clues to renew interest in the hunt which he was still profiting from in different ways.
Michel Becker only helped illustrate the book that is the support for the hunt and has taken over it when he passed.
As far as I know this was quite controversial because he had not knowledge about the riddles or how to solve them, and was only able to take over because there was a notarized enveloped left behind by the original creator which explained everything.