I protest voted because I figured I lived in a safe blue state where it wouldn't matter if one more cripple cast a protest vote. I had resolved not to protest vote if I was in a swing state, but I was still living in Maryland at the time of the General, so I figured it would be no harm.
Mathematically, it didn't matter, but knowing that I was a contributor to the popular legitimization of a Trump victory soured me on protest voting even in safe states.