Speeding is one of the leading causes of fatal accidents.

Tailgating is one of the leading causes of non-fatal accidents.

Sounds like it's safer for me to let people tailgate me at the speed limit.

Many of the people killed by speeding are not, themselves, speeding.

I’m not sure that is the case. Bunching together look like a higher risk to me.

Bunching together happens because of irregular speed. You have traffic clusters because the front is slower than whatever the "natural" speed is, but not so slow that people elect to pass.

If traffic is all moving in a narrow range of speed the clusters are smaller and less dense.

So does speeding.