Wu said that he learned that the text in the BlackRock Bitcoin advertisement released by Michael Saylor showed that "there is no guarantee that the supply of 21 million Bitcoins will not change", which caused controversy in the community. Adam Back said that it was obviously their lawyers who asked them to write this because they sell investment products. Their lawyers are just making sure that they will not be sued if the community changes the numbers and they sell Bitcoin ETFs. This is important for lawyers because they realize that this is beyond their control.