There were in the past icos that used that tactic with some success but to me that seems a cheap tactic, let people to decide what it is the best coin based on the the actual performance of the coin, the developers and how fast they can reach their goals instead of using the tactic of hiring a celebrity to promote your product, this is especially true because many of those celebrities are not really going to understand what they are promoting and could easily get in trouble with the authorities if they promoted a scam.

And that will be terrible for them since the thing they care more than anything is their public image and it will be tarnished if they promoted a scam.