Slow down a bit to create another buffer. You can even do this before they have merged, as part of the bit where you allow them to safely merge.

I think if you reflect a bit you'll find you are being the same kind of person as them, if you are getting angry that you have to slow down and give up space for someone else. I understand some people can be aggressive though, that can be frustrating regardless of the outcome.

It seems like a tragedy, but actually it can be a boon as long as you travel in neither the leftmost nor rightmost lane. The majority of the traffic entering your buffer will be exiting your buffer out the other side as soon as they can, so you can just chug along at a (greatly reduced, but) consistent speed. Meanwhile, the traffic to either side of you is in standstill, paralyzed by your bow wake.

Not to mention if that if somebody needs to come over, the proper thing to do is signal first. Then I'm happy to politely ease off a bit and open more space for them to come over safely.

It's the people who aggressively slide right over just a few feet in front of me (cutting off nearly all of my safety buffer) without so much as a signal that really drive me nuts.

> as their opportunity to travel faster

You're ascribing motive where you have no data to do so.

> travel slower and slower

Roads near capacity slow down. This capacity surge is typically highly predictable.

> tragedy of the commons style, by opportunists.

People can only drive one car. They cannot drive two at the same time to get there twice as fast. I don't think this logic applies.

That is a paranoid-survival oriented perspective.

> someone is taking your safety buffer as their opportunity to travel faster

Nobody is 'taking' something; we're all just sharing the road, and at little cost. People change lanes for many reasons, and sometimes to pass someone else and travel faster. That's what the left lane (if we're talking about the US) is for.

> results in you having to travel slower and slower to maintain the gap that is constantly consumed,

I understand the theory but that hasn't happened in my experience.

And even if five or ten cars got in front of you, how much distance is that? A random Internet site says the average midsize car is 16 feet; add 220 ft safe driving distance at 75 mph (says another random website), so let's say 240 ft per car x 10 cars is 2400 ft. In that extreme circumstance, it will cost you ~30 seconds.

It's self-fulfilling: If you act aggressively toward other drivers, they will respond in kind. If you treat them respectfully and politely, they act the same way toward you. People behave well and kindly, naturally. We are social creatures.