Well, I guess he stopped doing it at some date before 2007. That's why he told an audience of 500 people about it. He sorta "cashed out" by making it a fun story about him being clever, instead of a last magic trick. He must have simply gotten tired of doing this every day and seeing all those cards in the waste basket (or burning them?).
If he had indeed tried to pull that trick in 2020, a lot of people would have remembered that he said he was setting it up.
