The most recent “assassination attempt” was just drummed up by the media. I haven’t seen any evidence it was anything other than a man with some guns in his car who happened to be near the rally.
The Riverside county sheriff is the one who first used the term assassination attempt. Media uncritically repeated what the sheriff said.
Honestly, I’d be surprised if the venn diagram of “people who would keep guns in their car” and “trump’s base” wasn’t a circle.
There’s going to be a lot of false positives in an environment like that