Growing big is difficult. At the same time sustaining at the same position for a long time is also very difficult. One should be always cautious and work at their maximum capacity to retain the place.
Especially in some fields like sports, movies, TVs etc., unless otherwise, you perform well, you can't stand. If you stop performing, you will definitely perish. We see many actors ruling their field for some time and later on, they will be forgotten by the audience. Only a few personalities will be remembered and respected for long.
Fame will come to you after a struggle and doing many works which are remembered by many people. But any small work which is not up to the mark may change the entire situation. That is why people in power or big positions should always be alert.