A former Green Beret Sniper has something to say about this.
And where does conspiracy theories merge with incompetence as well as neglect. A former Secret Service Agent has this to say about the latest news that the USSS had actually spotted this kid before he even got on the roof.
JFK was assassinated by a combination of the CIA, the Mafia, and Lyndon Johnson and others in the Democratic Party joining forces in an age where that was possible, and where a naive world though such things were not possible.
Jack Ruby, a mob associate, shot the patsy Lee Harvey Oswald.
JFK’s brother was not shot fatally by Sirhan, that was proved conclusively by the LA medical examiner as 2 bullets grazed RFK while the rest went into the ceiling as RFK’s, non FBI security, jumped on him. Instead RFK was shot 4 times from the back, and upwards into his body by a security guard imposter with links to the CIA.
Sirhan was a patsy too.
There was no neglect by the security forces in the above two cases because most were not part of the conspiracy.
The current head of he secret services is a woman. Her previous job was head of Pepsi Cola security. In other words protecting executives. She was an appointee of the Biden administration. Her experience with the security services and FBI is of course a number close to zero.
Four years ago President Trump held a rally not 5 miles from the current assassination location. It was at an airport, or close to it. As a local resident stated, who attended both rallies, every roof top at the earlier rally has spotters and snipers on them. It was so tight his daughter remarked how tight it was to get in , and how many spotters etc looked down on the place.
Rather than accepting the maps of the Trump assassination broadcast on most Mainstream media, with its 3 points, shooters roof, snipers roof and Trump stand, you zoom out on Google you will see the great number of buildings behind the shooters position.
His was not a single building, there were multiple buildings. None had spotters, none had protection snipers.
My first thought when I first saw it on TV coverage was how thin was the sniper protection, there appears to have only been one.
The local resident also stated that border protection was thin to non existent, and that locals knew how to circumvent it as there were no choke points to control the crowds.
As for the protection detail, they looked and behaved like rookies, it was their first dance.
There was no patsy, apparently. However who knows, someone may have got to the shooter through the dark web.
Or was the head of Pepsi Cola security, that patsy. I think so.
No Minister 
”Her experience with the security services and FBI is of course a number close to zero”
Are you quite sure about that?
I stand corrected, she has 25 years in the secret services, before she went to Pepsi she had worked on the Biden security detail too.
Only the second woman to hold the position. As for her emphasis on training and setting up protection for such an obvious target as Trump well perhaps she was manipulated.
So she has experience, whether she is competent is a moot point.
Of course she is being asked to resign for this failure, and so she should.
How is it all coordinated?
I think there is a lot here, probably too much for a short piece so I will try to be concise.
If two or more parties are acting in concert, towards a common goal, then there has to be some channel of communication to coordinate their actions, so what is it?
I think that looking carefully at these events is not only important because of the events themselves but also because for what they show us about the way we think.
Try looking at the event from a deductive perspective (general rules of reality producing specific events) not only from an inductive (specific events leading to general conclusions about reality).
Then try to consider it from different points in the timeline.
I’ll just consider the death of JFK here. Most people will start from Nov. 22, 1963, and work inductively backwards from that point into the past. But what would it look like if we start in the past and worked deductively towards the future?
Let’s take Jan. 20th, 1961, the day JFK was inaugurated. If you are correct that he was “assassinated by a combination of the CIA, the Mafia, and Lyndon Johnson and others in the Democratic Party”, and those disparate groups were working together to achieve a common goal, and they did achieve their common goal, then how did they coordinate their actions from the first date to the second date and also make it undetected from that day until now?