When celebration becomes so important than finishing the race, the outcome could be completely undesirable: losing the race. That is what happened to, as shown in the video, Tanguy Pepiot in Oregon.
In fact, it could be questionable whether what he did was unambiguously celebrating, in his own world, the end and the result of the race or whether he was trying to get energy from the crowd during the challenging task of finishing the race while maintaining leading position.
In any case, Tanguy Pepiot’s experience could be relevant in other realms of life. Early celebration could indeed mean complacency.