The Secret Service is part of the government. And Trump gave them a hell lotta headaches already. You think they would all conspire with him to stage this?
With every event like this you will find someone who has saw something beforehand.
Did you ever get hit by a car, had a bullet hit near you, or had other close call accidents? Anyone in such a situation will be jacked up on Adrenaline, or just straight away under shock. You do not act rationally under shock I once got hit by a car and just wanted to continue walking. It took two people to tell me to chill and they will call an ambulance.
And final thought. the Secret Service is trying to rush him off stage, you see that in the video. But they are not going to shove him to the ground or drag him bis his legs.