As someone who didn't vote, no, I would not have changed my decision given the outcome, and this "lesser of two evils" justification crap is exactly why. Enjoy your shitty country.
It sounds like you are the apathetic voter in this scenario.
Of course, the Democrats have themselves totally acceded to this scheme.
This is a common line used by leftists who are angry that Trump won and are looking for someone to blame. Third party voters make an easy target, and the left has long felt entitled to the support of third-party voters.
But this entitlement assumes that third party voters would otherwise have voted for Clinton, which is a pretty strong assumption that also doesn't really hold up against the polling data from late in the election. Johnson took more than half of the third-party vote, and had he not been running, most Johnson voters would either have voted Trump or not voted at all.
Trump didn't win because of the few voters who voted third party. He won because of the 63 million people who voted for him. If you want to blame someone for Trump's victory, blame them, not the 7 million who chose not to vote for Trump.
Effectively, in a first past the post electoral system, any vote that isn't for the major party that most closely aligns with your views is a vote that supports the views least aligned with your preference.
I do see some listed counterexamples to the "law", and also a note about occasional upsets where the parties get completely rearranged.
If both major parties suck, how do I ask for an upset? Is it by fuming quietly and voting for the lesser of the two evils, or by saying "no, fuck you both"? Or does the fact that any upset probably won't happen this election mean that it's part of "the long run" where per Keynes we're all dead, and so it doesn't actually matter?
Do the major parties just ignore any non-major-party vote, or do they analyze it to tweak their platforms for next time? (And, is this consistent over time and space? I'm hearing that it seems to be the case in the US now, but in the same breath I'm hearing that that's a recent localized disaster.)
The Wikipedia page is a tremendously short summary, and yes, doesn't go into depth about the implications of duverger's law.
I strongly suggest digging into the literature around it, which does bear out the thesis I states above.
If both parties suck equally and no party is more closely aligned to your preferences than another, I suggest you enter politics yourself. It's just made up of people not too different from yourself.
I've actually thought about that a bit, and don't think I'd enjoy it enough to consistently put in the time needed to ever really get good at it.