Opting out does not save you anything because voting doesn't cost you anything in the first place.

The bet here isn't voting; it's elections. An election is an essentially random process where depending on the result things change either for the best or for the worst. If you somehow quantify how far America is from fascism (say, in terms of how many Republican terms it would take to go from the situation at hand to full-blown fascism) then you can model elections as a bet where you're forced to participate and don't get to choose your stake. Again, under this model (which should be accurate since the conditions for its application are all there) you will end up at fascism unless you change the game you're being forced to play so the odds are in your favor rather than the fascists'. I also want to point out that this isn't an analogy; it's a model. I'm simply taking a principle that exists in one field, making some simplifying assumptions and applying it in another. What I outlined here isn't a "what if" analogy; it's one step removed from a mathematical certainty.

It's more like we're on a sinking ship and bailing water. The ship is going down if we don't patch the hole, but bailing water still buys us time so that we can make more attempts to patch the hole. Except in this metaphor, bailing is something that takes maybe an hour of your time once every two years.

I have no problem with the act of voting itself. My problem is with... everything else that happens during election season. The whole idea of unity with liberals (aka Democrats) against the right is evidently a failed preposition, and the reason for that failure is specifically that the Democratic Party is invested in the game's present state and will force you (or, more accurately, already forces you) to cooperate with them to maintain the game before you're allowed to be "united" with them. To borrow your analogy, the Democrats are the ship's captain, who is helping you bail water but only on the condition that you don't patch the holes (and yes, there's more than one). You're not even supposed to point out that neither you nor him are patching the holes. Instead, you and the rest of the crew are supposed to just keep bailing and ignore the rising water level. And to be clear, the bailing isn't just one thing you do every two years; that doesn't begin to capture the opportunity cost involved. Your bailing in this analogy is voting drives, canvassing and other outreach on behalf of the Democrats; it's political donations; it's suppressing criticism of the DNC (attempts to get the captain to patch the damn hole) in the name of unity against the far-right. The actual voting is only the end of this long string of actions that sap energy, money and credibility from the people who would otherwise be out there actually patching the damn holes.

Okay analogy over, back to the real world. The DNC should've been fucking flayed alive when they tried to push a pro-genocide ex-DA on Americans, and instead all they got was progressives hushing down other progressives in the name of "unity". I'm sure you can think of all sorts of examples of this in action, but here's one to drive the point: the progressive reaction to the Uncommitted Movement. This was a large movement that had gained momentum in an attempt to push the DNC from proto-fascism and into the sanity, and what did they get from not even liberals, but progressives who should have been their most ardent supporters? "Hold your nose and vote for her." Not a nationwide solidarity to force the Democrats to back down on their most unpopular policies, not even tepid support or apathy, but active, emphatic opposition. That's not the stuff of democracy; that's a dictatorship where you roll a dice every four years to find out which boot will step on your neck until the next election.

I should note: I'm not advocating for passivity or apathy here. This shouldn't be a reason for you or anyone else to stay home and give up; it should be an impetus to organize, embrace solidarity between workers and take on the capitalists and their supporters. Act, but act according to your own conscience, not according to the DNC's agenda. This is especially important right now because the Democrats won't save you from fascism even if they wanted to, but even if democracy and the DNC both survive Trump, next time you be on the side doing the flaying and not the side practicing cannibalism on behalf of your blue donkey overlords.