It’s hard to feel otherwise when operating under a FPTP system, which is basically intentionally built to shut out third parties. In fact, one of the prominent benefits of FPTP is that it’s incredibly difficult for an extremist party to find foothold - as opposed to what is seen all over Europe currently in places with party-list proportional representation.

Whether the third party candidates are naive about their chances, putting themselves out there as an act of protest or intentionally diluting the vote is impossible to say (and I suspect there are some out there in each category).

In the end however intentions don’t really matter - the practical impact of third parties in an FPTP system is diluting the vote.