The FPTP voting system means everyone is held hostage voting for the party they hate the least. If you vote for a third party you just make it more likely the party you hate most will win because the vote is split.
Obviously things still wouldn’t be perfect with a proportional voting system but I think it would take some power away from capitalist oligarchs because we will be able to vote for a party we like without just making the fascists more likely to win. The issue is the only two parties you can realistically vote for are highly incentivised to not change the voting system because they will lose a lot of the power they have.
Or how about everyone who wants to vote 3rd party, votes 3rd party?
I know it’s a little different because my country has proportional voting system, but the first two elections the party I vote for was below the limit to be in a parliament. I still voted for them as did others and now it’s one of the stronger parties.
If everyone who doesn’t like both the parties starts voting 3rd party, you have a chance.
That’s the good 'ol spoiler effect in action lol
Think about it on the constituency level, say you have a constituency with 100,000 people. One year, 60k people vote for party A and 40k for party B so party A wins. But during during the years before the next election people become disenfranchised with party A so they start voting for party C who they like more. In the following election, party A gets 30k votes, party B gets 40k votes again and party C gets 30k votes. Because FPTP is a “winner takes all” system, party B is now takes that constituency which is the the party A and C voters dislike most, even though party B got less votes than those other two. This is called the spoiler effect. When this is happening all over a country, sure maybe some constituencies will flip but for each that does like 30 will have the vote split leading to a probable landslide victory for party B.
Sure in your country, your vote was also “wasted” if your party of choice never entered parliament I suppose (although if you get to choose multiple parties in order of preference where it defaults to your second if the first doesn’t get enough votes then it isn’t wasted) but the ecosystem will be much more favourable to new parties growing because the way the voting system works makes it actually possible for them to do so. So the vote isn’t wasted like it is in FPTP.
CGP Grey has some great videos about FPTP on his channel if you’re interested in a better explanation that I can provide.
The spoiler effect was very evident when Ross Perot ran during the 1992 presidential election which put Clinton in office.