People acting in their best interests is how it happens. It's an electorate avoiding splits. Given the system you're voting under - you should vote for someone who has a chance of winning. Otherwise you might write-in some special favorite candidate that no other human being cares about, and accomplish literally nothing. Voting for a third party with single-digit support is not much better.

People voting against their own interests would be... not bothering to write in a second preference. It is the same fuckup: someone who cannot imagine their very favorite guy losing.

[–] emergencyfood@sh.itjust.works 1 points 4 hours ago

Given the system you're voting under - you should vote for someone who has a chance of winning.

The problem is that who 'has a chance of winning' is decided by who people vote for.

Voting for a third party with single-digit support is not much better.

Uh, that's what the Sri Lankan voters just did? The winner this time had 3% of the vote-share in the last election.