Blackrock made a Bitcoin video explainer. Cool, isn't it? But ...
Voice: "Bitcoin has a fixed supply of 21M"
On-screen text: "There is no guarantee that bitcoin's 21 million supply cap will not be changed"
Why should they add that?!
Discussion
Spoke about this with some friends the other night. We think it’s mostly a legal thing. The only way the hard cap would be changed in future is through a hard fork, and black rock could choose to follow that fork. Although none of us would follow it at all, maybe they will. So they don’t want to legally shoot themselves in the foot I guess. That’s our guess.
Yes, it definitely looks like some they had to add after lawyers saw it.
Luckily, Bitcoin doesn't care.