The issue with comparing your self to others is how much you become obsessed with achieving their existence. To exist as an individual is paramount. When an individual sees another individual and makes existing as them their goal, the only result will be destruction and disappointment. To want to be LIKE someone else is OK to a point. If you want to be someone else entirely, this is a goal you will never achieve.
It is a bad thing to compare ourselves to others. This is because we are all different, have various aims in life, and shouldn't be expected to live up to what others stand for. People should have their own sense of self and find out what it is they are really looking for. If we get obsessed with competing with others for the same things, then we will never fulfill the aims of our own identities.
It seems comparing ourselves to others can never be a good thing, as it's usually done in a negative way. Like, that person has more money than I have, or that person is prettier (or more handsome) than I am. There's really never a positive point to comparing yourself to other people, even in role model situations, because it's possible that person will eventually let you down. Instead, you can set standards for yourself not based on other people.
It's usually a bad thing to compare yourself to others, because then you start to think either too highly or too lowly of yourself. And this sort of overthinking is dangerous. The moment you start harping on others and comparing yourself, life will begin to pass you by very rapidly.
No matter who you are or what your personality describes about yourself, one should never compare himself or herself to other people, especially actors and people in the music industry. If one wants to compare himself to someone, I believe that person should be a positive role model that can influence our society in positive ways.