Be yourself. Everyone else is already taken. -Anonymous
The mere act of looking up to someone or having an idol is not problematic. Having an idol only becomes a problem when you find yourself placing them above yourself. This is a common phenomenon where you have someone you admire and you think they are awesome, so awesome that you subconsciously place them into a God/Goddess category where you sabotage yourself by saying that you could never be as great as them or do what they do. The irony here is that the other definition of idol is "an image or representation of a god used as an object of worship."
Another problem that arises from having an idol is that you might find yourself mimicking certain things that they do or say without question so much that you lose yourself. Or perhaps this manifests itself in the form of so-called "fandom accounts" on social media where people obsess over and mimic the idol. These people dedicate so much of their time talking about, organizing, buying, and creating things to honor their idol, that could've been used to actually better their life. In order to become unstoppable, you must become your biggest inspiration, your biggest idol. Drooling over the lives of others may help you in some ways but eventually you need to become your own person.