The 'Stay Too Long ' singer thinks the rapper proved his ego is out of control after he invaded the stage at the 2009 MTV Video Music Awards to tell the audience Beyonce Knowles should have won a prize that went to Taylor Swift.
Plan B - real name Ben Drew - said: "Kanye knows he's a f***ing idiot - I ain't gotta tell him that. He's lost touch with reality but it must be hard when you get that big."
The London rapper admitted you needed a big ego in order to succeed in the music business, but blasted Kanye for being an example of someone who has gone too far.
He said: "You only get into the music business by having confidence and determination. You need to convince people you are going to make it. That's the amount of ego you need to survive and Kanye certainly falls into that category."
Plan B, 26, is determined not to follow in Kanye's inflated footsteps.
He added in an interview with the Daily Star newspaper: "I'm glad things happened like this, slowly, because if they hadn't I'd be up my a**e too."