Correct me if I'm wrong, but doesn't American constitution apply only to US' citizens? Even in the ideal case, were it to perfectly protect Americans from three

Correct me if I'm wrong, but doesn't American constitution apply only to US' citizens? Even in the ideal case, were it to perfectly protect Americans from three-letter agencies' weaseling, it offers absolutely zero guarantees for non-citizens, which is 95% of world population or so. Americans could pressure USG to stop spying on foreigners, but why would they? I don't see any incentive for an average John Doe to do so. So, overall, there's not that much of a difference for most of the world. One might even argue that for outsiders Chinese relatively stable direction and autocracy is marginally better than American flipping every 8 years, since it allows you to better assess threat profile. Edit: added a bit about assessing threat.