Hello @chbartist!
More than learning to tolerate rejections, we have to learn to decipher the message behind each failure, because the purpose of the failures is not to harm or block us, these are just consequences of the failures. The purpose of the failures is to teach us and help us to evolve as people in any area.
The message that Jack Ma found from my point of view, is that we should not continue doing what everyone does, but find new things with which we can contribute to the world. And that was what happened with Jack Ma after so many rejections, I think he received so many negative responses because maybe he was not very competent doing the things that others do, and he also had a lot of competition.
But instead, he found a new market niche and with the new possibilities of changing things in China, and that is why he is now so successful. That is why it will always be important to give space to innovation in our lives.