There are several reasons.
First of all, Kaka himself has been plagued by injuries since the middle of his career. His sharp kicking method itself is eating the body. With the growth of age, it is almost the age to consider retiring (35 years old).
Secondly, for both sides, this is not the best choice-for Kaka, who is not poor in money, the Super League has no other attraction except more money. For the well-funded Super League teams now, senior foreign aid is not the first choice.
Perhaps both sides have considered each other, but not to the point where further in-depth negotiations or tug-of-war are needed. Simply put, even the two sides have not reached the point where you don't marry or you don't marry.
Third, Kaka himself cares more about his image. As a former Golden Globe winner, he is not short of money, and there is no need for him to take risks for money. Didn't you see that he chose Real Madrid instead of Manchester City when he left AC Milan?
This shows that money is not the only factor in his choice. As the saying goes, it is better to miss each other than to meet each other. It's best to keep the best scenes in your memory.
Therefore, the rumors at that time were only rumors after all, and perhaps both sides had considered it, but they did not reach the point where further in-depth negotiations were needed.
What other reasons do you think Kaka didn't come to the Super League in the end? Welcome to add.