This does not mean trading is inherently stealing. Without government sanctioned advantages (such as in the Bitcoin market), the only way to profit from trading is by moving assets from where they are available to where they are scarce.
It's not the only way. Thieves have been very inventive throughout history. Today they have things like "derivatives" and high-frequency trading that have nothing whatsoever to do with moving assets to where they're scarce and everything to do with accumulating undeserved money (while also creating economic instability, but who cares, right?).