The US is in this weird place where voters still hold nearly all the power in elections, but nobody feels like their vote matters because they never get what they want. This is by design, the general election is designed to be about compromise and getting the closest representation of the will of all the country that one person can possibly hope to be. Biden and Trump are who the averaged (Voting) American thinks should run the country whether you like it or not.
Primaries are for making statements to the candidates and the country then general elections are where, in a democratic system with a one person branch of government and multiple parties, you will almost certainly have to compromise at least a little because somewhere in the process your perfect ideals were overruled.
Not voting when able is throwing away any right to complain, if you didn’t exercise your right to representation in the primary, then you voluntarily waived any standing to complain about the general election candidates, but should still choose one as this is the only step in the presidential election process where one candidate is guaranteed to lead the country and not voting is again throwing away your most accessible tool for representation.
This doesn’t mean you aren’t able to take other actions to influence policy after an election like protest, demonstrations, or even seeking some level of office yourself.
This needs to be more known, Not voting isn’t protesting a candidate, it’s only hurting those who agree with you most.
Third party is only slightly less useless with our current election system, at least it exercises ones representation, but is counter intuitive as it also makes whichever of the larger two parties that more closely aligns with you less likely to win. And this becomes more and more true the larger the 3rd party becomes and skews the whole point about the president being the averaged choice away from the center. Currently it’s better to influence one of the major parties instead similar to what we’ve seen with the democratic party and unions and the republican party and authoritarianism.
You are quite dug in on the presidential election, but do keep in mind you are usually also voting for local/county positions on that same ballot, where one vote often makes the difference and has a more immediate impact on your interests