Claim: The attempted assassination of Donald Trump was able to happen due to non-malicious incompetence.

The U.S. Secret Service said it had turned down requests from Donald Trump's security detail for additional resources in the two years leading up to his attempted assassination last week, the New York Times reported on Saturday, citing a spokesman.

This is a reversal from earlier statements by the agency denying that such  requests for the former president and Republican presidential nominee  had been rebuffed, the newspaper said.

I think trying to establish a timeline with events is useful. 

Here we see the claim thay he was a known person of interest over an hour before his alleged shooting with increasing levels of suspicious activity as time passes. This suggests negligence or incompetence at best. 

Maliciousness is hard to prove and is certainly underermined by this evidence.