It's a herring; a distraction signal for which the CCP can garner analysis of the United States decision response calculus. If US were to attack the balloon, it would set a jurisdictional precedent bringing into question many considerations of the disputed Taiwanese and South China Sea airspace, perhaps even geo-sync satellites.
Nobody's talking about the spy sats that are further up, balloon is just a caricature to drum up support for either side, humiliate one party, etc.