I am trying to make sense of his decision.
1. His dream of becoming a world champion is realized.
2. It appears that he had enough of people asking questions in many an interviews where it was made apparent again and again, how Lewis is stronger than him and how he handles it.
3. He probably feels like he does not have it in him to repeat this success again.
4. Was he unhappy about his new contract that was for 2 years and not of that he wanted, which was for 3 years? Now that he has won the WDC, he calls it quits. Sort of "In your face Toto" kind of stuff.
5. Would he have quit regardless, after this season even if he would have lost? Because it take s a lot to keep coming back after season long struggle that only fetches a defeat. 3 years in a row.
6. I remember Dr Zetche had mentioned that Wherlein is the future. So, was there some sort of agreement struck between Nico, Toto and Zetche to help him win a title and retire, so that Wherlein can come in for next season. Ocon was provided a good place in FI and Wherlein was held back.