Addiction can affect anyone, even stars. Look at Mike Ribeiro, who could have had a stellar career without addiction.
Indeed, Nichushkin reportedly failed a drug test, which is against the regulations, especially in his position.
He's now in the third stage of the NHL Player Assistance Program, yet he still failed a screening test. The sentence is a minimum of 6 months without pay, and he'll have to earn his place back if he wants to return.
Other players have struggled with addiction, including Alex Galchenyuk, the former Canadien. He got into trouble with that.