21 years of saving Zelda, was enough torture for one man. Even Ganon was fed up of coming up with elaborate schemes to kidnap Zelda and Ganon wanted ultimate power, nobody else cared.
Other aspiring villains tried but only Ganon could do a good job really.

Anyway, back to Link. 21 years is a long time to adventure and thus Link decided to retire. His aim with a bow wasn't quite what it used to be. Some other green cladded boy would have to do it. Groose has always had a crush on Zelda but unfortunately his elaborate hairstyle didn't quite meet the specification. Plus, all the other characters where eccentric characters from past games who wouldn't even make it past the first dungeon.

Ganon also was forced to retire. His determination to get the triforce had worn him out and he couldn't function as an evil villain anymore. He realised that somebody had to take over his role as a villain. Him and Link then bumped each while pondering over a replacement.
"Hey Ganon."
"Hey Link."
"Long time no see."
"Yeah... I just haven't been doing well recently..." sighed Ganon
"Neither have I..."
"Somebody has to take over our jobs eventually..."
"That's if Nintendo bother to find people." ranted Link
"Yeah, I mean they never think of original stories so how will they find a new character?"
"We could swap roles" said Link "That woman has been bothering me for too long, I want revenge! I'm also fed up of my annoying assistants!" remarked Link
"The hero always wins so I can finally achieve glory!" said Ganon.
"So it's agreed then." said Link
"Yeah!"

Link did not realise that this was an elaborate scheme by Ganon to finally get the power of the triforce...

Link realised that being an evil genius was hard. How does one come up with an evil plan? Suddenly he realised that he could easily destroy Hyrule. He had something Ganon never had. Navi.