It's because CashApp lets you buy and sell bitcoin, that is, CashApp is buying this bitcoin so it can sell it to customers [1]. It's not speculation on the part of Square or Jack Dorsey.

All this speculation about speculation is wildly disappointing.

[1]: https://www.investors.com/news/technology/square-stock-sq-sq...

> Square said revenue jumped 141% to $3.16 billion as more Cash App users bought and sold digital cryptocurrency Bitcoin.