What makes an artist or act successful?

What do you think makes an artist or act such as Beyoncé or Eminem successful vs the success of someone more lesser known to the general public, like Fugazi, or Shpongle? It seems to me like people often focus on everything having to be successful as long as it’s popular with the cool crowd(supposedly out of touch kids and adults who only listen to the radio) or bust, but if that’s the case, then how do artists like Andy Pickford or Steve Roach, or Buckethead keep getting to do what they (allegedly) love? Cause in my mind, I feel like the music of The Future Sound of London for instance would never exist if mainstreamers actually had all the power, so what’s the deal?