At this point, we know very little, but with what we do know at the moment - for this, you'd need:

• someone willing to be taken out as the shooter, willing to or being tricked into shooting blanks, or an extremely elaborate plan to switch in a body (you also have to acquire and prepare somewhere) in front of witnesses and potential cameras
• someone without blanks firing to explain the other bystanders dead from bullets
• complete control over the subsequent investigation, to make sure no one looks into it properly, which would make all the people involved in the know

It is still an extremely, extremely unlikely scenario

Or just use a razor and actually cut your ear. I'd say someone took their shot and missed. He happened to turn his head at the last moment, or the shot would have made a solid hit.

The reports I am hearing say that at least two people besides the shooter are dead, which probably is where (some of) the other bullets went. Dude is a coward, but also a narcissist, I assume he noticed that the Secret Service had already killed the shooter, so immediately switched into "I am invincible" mode.