Political consultants wouldn't agree with you. Third party voting is often seen by political consultants as basically "tea leaves". It is an indication of future trends. Not voting doesn't really help much, except for perceptions of "enthusiasm". But third party voting is seen as an indicator for future elections. They'll all admit though that it is easy to misread the indicators. A third party candidate may merely be an indication that a particular candidate, especially an incumbent, isn't popular with some section of a party, and they are looking for the "anybody but" candidate. The issues upon which they are running may have little to do with it. Perot is often seen as one of these. He was the "don't like Bush, can't vote for Clinton" candidate.

I tend to agree that third party voting is horribly dangerous depending upon what state one lives. One can think they live in some sort of "blue wall" state or "safe" state in which one can vote third party with little actual consequence. But I suspect there were folks in Wisconsin, Michigan, and Pennsylvania who thought the same thing.