Not sure I agree.He has a lot of faith in his own abilities and loves to be challenged. That might be a challenge too far though ?
If anyone can challenge Hamilton in the near future, then its going to be Verstappen - assuming he doesn't have a huge accident, which IMO, is a distinct possibility, unfortunately.
It seems Rosbergs reasoning was partly due to the fact that winning the Championship took so much out of him, that he didn't fancy doing it all again a year later. No doubt with the knowledge that he wasn't likely to be that lucky two years in a row.
That, I suppose is the difference between him and Hamilton. It drained Rosberg, but Hamilton really thrives on it as it comes so naturally to him. It seems he was born to drive racing cars at the limit, and its no big effort for him to do it.
From memory the only other driver to do what Rosberg has done was Alan Jones. He won his and Williams first Championship and then turned down a huge amount sum of money to carry on. He had promised himself and his wife, if hew became world champion he would stop.
He changed his mind a couple of years later and came back, but it was a big mistake. Things had moved on while he was away.