Why U.S. Military drones patrol above the 50 states?

I was thinking today why the U.S. military patrols the 50 states with military drones and has done this for the last 10 years without telling the people about this.

When I thought about it more one reason might be that they are there to shoot down foreign and criminal drones before they become a threat to military or government sites or to prominant individuals in our country.

However, likely people have been shot by drones in the U.S. but they haven't been reported killed yet. It is likely that people have been shot by drones all over the world at this point.

However, this likely would be redacted from the news most places because of drones used now by most militaries of the world to maintain their governments ongoing by whatever means necessary.

What is interesting about the larger drones like the Predator series is they can stay up 24 hours or longer because pilots can be changed on the ground or assignments can be given to fly that drone autonomously so no one is flying the drone only itself following orders.

So, literally any military drone even within the U.S. might be given literally ANY assignment and do it completely by itself whether it was surveillance or the elimination of a threat to our government or the threat of a group of criminals.

I believe the limit on Predator drones is around 36 hours or more being aloft and flying around. Also, they are relatively quiet because they can also glide pretty good too because of the way they are designed. So, the engine does not have to be on all the time. So, most people won't even know they are there especially at night.