If lets say 10% of people vote for the green party. We know that what people want relates to their messaging and they’d try and take voters away from them as it’s easier than taking republicans or people that refuse to vote since you know what the green party stands for. That’s different than voting for the social democrats and so on.
You can’t lump options 3 and 4 together like that.
Not voting sends the message that people are dissatisfied or feel disenfranchised. Now if the Democrats win they won’t care to change. Or even if they nearly win. But if they loose badly they’ll have to cater to these voters. And thus a pivot would be in order. But like we’re both said, not voting harder to take get a party to move in that direction
For what to happen? Your statement is incomplete