"I think it comes back to wanting to take on, in his words, a new challenge".
Grand Prix racing was stunned when Ricciardo revealed his move - but Ricciardo said it was vital the world realised there was more to him than smiles and shoey celebrations.
"So as I said for me it is a bye bye, but who knows what will happen in the future?"
Ricciardo's sudden refusal of a new deal left Red Bull scrambling for a new driver for next season. I feel strong, feel a good level and want to say bye-bye to this sport when I am strong, not when I am not competitive or have no place to go.
With the contract stuff people assumed I was pretty much done with Red Bull and ready to sign, but I'm pretty sure I always just said I was close to doing something. I don't really care.
"There's been times this year that I've felt exhausted, maybe a bit jaded, and for the first time in my career, not completely enjoying F1", Ricciardo told Fairfax Media.
Alonso said that criticism was at odds with the interest Red Bull had shown in him.
"So that is why I wanted to come and check out Super Formula first-hand". It wasn't easy. A few sleepless nights trying to come up with the best conclusion for myself, ' he told Fox Sports. "It might be an inspired choice, it might be one he regrets".More news: How to Watch Newcastle vs
Red Bull could field two of its junior drivers in Super Formula next season, according to its motorsport advisor Helmut Marko.
Alonso's decision was one of a series of driver moves announced over the summer break, which ends with the Belgian Grand Prix this weekend.
Without divulging the intimate details of their negotiations, Abiteboul said Renault convinced Ricciardo to come across even though it wasn't the highest bidder. "But he didn't", Marko told Austrian TV station Servus.
He told a news conference that "it was a decision that probably I started thinking about previous year".
"It all ended very amicably and basically they're sorry to see me go and appreciate what I've done and given to the team".
The Spaniard's comments appeared to be at odds with Red Bull boss Christian Horner, who suggested after Daniel Ricciardo's decision that Alonso was not under consideration. Second, I don't think we were the highest bidder in obtaining Daniel, without going into details.
But if I'm honest with you, when I did make the decision and said "this is what I'm going to do" and I made the calls and did what I needed to do, I felt a weight was off my shoulders and a big degree of stress was released.