“If you swing at the king, you’d best not miss.”

We know this involved gov agents, without a doubt. We know the gunman could not have acted alone.

If so, there’s no way that those people would leave everything up to a 20 year old, even if he had extensive training, which he didn’t.

We don’t know the details, but just like with JFK, there is no way there was only one shooter if the shot was at range. One or more people would have absolutely been in place as crossfire/insurance/control.