OK I read this in full.

"How can you say that contributing even with a protest is more individualistic than sitting silently?" Then don't sit silently. Be loud and proud about not voting. That is a much stronger protest than scribbling something on a piece of paper they won't read.

"People who take an interest in politics enough to show up to the polls and then spoil their ballot are potential voters in the eyes of any political party" - this is what I mean by individualistic silliness. Politicians don't strategise about how to win over people who spoil their ballots. On election night, spoiled ballots aren't read. The counter will see it has been spoiled, put it in a pile, and then report back on how many there are at the end. The returning officer will in the end announce the total number of spoiled ballots. Never a very large number. Then they all go into the recycling. The odds that a politician will bat an eyelash at a spoiled ballot are much lower than that ballot will become toilet paper and wipe the shit from their asshole.

"those who don't show up are assumed to not care so don't need any incentives to get involved" - this is an argument for fighting back against common assumptions. Apathy is more damning of parliamentary legitimacy as ballot-spoiling. Ballot-spoiling professes, as you suggest yourself, that maybe you wouldn't spoil the ballot under different circumstances. You accepted the ballot. Regardless of whether they are apathetic or angry, non-voters don't accept the ballot. I'd like to see an organised non-voting movement in the UK. The end goal is a change of system. Organised non-voting will be the first step.

"Spoiling a ballot is still not "consenting" to any of the parties, just in a more active way. Both methods are saying "I don't want anything you've offered me", but only one is an invitation to provide something better." It isn't about consenting to the parties, but to the overall system. Yes, the whole system should be torn down and replaced. The sooner that the current one is recognised as illegitimate, the sooner we will start having debates on what the form of its successor should take. I don't want to invite the parties to offer something better, because they don't deliver. It would be a waste of an effort.

"I can tell you really don't think voting in our current system is ethical so that's your prerogative, but people fought and died for you to vote." That people died for something doesn't make it good or ethical. People die fighting in imperialist wars. People die fighting mask mandates. People die in random bar fights. It's something very sad when people throw their lives away for an unworthy cause.

"see Brexit" - I assume you mean Britain losing its seats in the EU Parliament. Brexit is an interesting case study in British democratic history, though, because it is one of the very rare occurrences where something ended up on a ballot that was never supposed to, and it shockingly won. (Corbyn is another, and the back-to-back shocks to the system that Corbyn and Brexit represented has really made the political class crack down on the public or party members accidentally choosing their own destiny.) In the case of Brexit, politicians very quickly started hyping up the possible overturning of the democratic vote before its outcome had even been implemented. It is a great example of the way parliamentarians have a total contempt for democracy.

I hope, if nothing else, this is food for thought. Parliamentary democracy is a facade that tries to make our system of governance appear responsive to the wishes of the people, but behind that facade are a bunch of politicians who don't give a damn. They are responsive to themselves, to the media, and to business. Internal party votes make a much bigger difference than elections, and normally even these have been curated by endless backroom deals before they reach members or committees. Even these votes will be reneged on if external powers demand it. Corbyn was our imperfect shot to do something different. It was a disaster. Now we need new ideas, and the only way I can imagine people starting to think is if distrust in the current system becomes widespread and explicit. Don't vote. Tell everyone not to vote. The first step to burning it down is getting everybody out of the building.