Alarm should be a precursor to action. In this case, what action should an alarmed person take?

To put another way, the expected value you should be evaluating isn't something like the megatons of a strike but the difference in outcomes of a strike or miss vs your actions. I would guess there are few meaningful actions you could take (you have no control over or knowledge of where it would strike, if it strikes). With the delta in outcomes close to zero, no alarm is reasonable.

You might review your emergency evacuation plan (or create one if you don't have one). It's very unlikely to be needed in this case, but for all causes over your lifetime, the chances it turns out useful are probably not negligible.

I'm principle, if we knew the asteroid is going to hit a populated area (which we would in 2026), we could seriously consider deflecting it to either miss earth or hit the ocean.

Here's Scott Manley from two weeks ago.

https://youtu.be/Esk1hg2knno

There's nothing to do now or for the layman, though, as you said. Also, this opens the fun possibility that people could redirect an asteroid into a city, but unless they can do it secretly or deniably, nuclear weapons are probably easier.

These types of probabilities aren't absolute in the same way that flipping a coin has 50/50 odds.

Its more like a monty hall problem, each door either contains an asteroid collision, or proof that its not going to hit earth. But we dont have perfect information on the size, albedo, spin or orbit of the asteroid so most doors are closed. Each time we open a door and do not find the asteroid, the probability of finding proof of an earth collision AND a proof that its going to miss will go up.

Calculating a spacecraft/asteroid trajectory is already precise enough to land a mars rover in the correct target area. But we know the exact properties of the spacecraft so all the doors are open.

This is not the type of asteroid that would end all life on earth. It has the ability to destroy a city, but even if it hit the earth, it would probably land in the ocean or a remote area where few people would be harmed. We should not be alarmed about a 2% x 0.28% probability that a city or town is destroyed in ten years.

Let's also note we are aware of the possible corridor of impact, so if you don't live near the equator in Central America or Africa the chance of hitting YOUR city is 0%. News articles conveniently leave out this detail so they can continue to spike fear and clicks with every micro-refinement.

Yeah, even if it hits, chances are it'll end up in the ocean, and the predicted area of impact isn't anywhere near my home.

I still think the odds of something more destructive happening is higher - earthquake-tsunamis, hurricanes, nuclear warfare, large volcanoes, covid25, etc.

The current risk of collision is comparable with the background risk of this type of impact, which tend to happen about once per century.

It’s been as high as 3.1% No one would be cool if I pointed a gun at them and said there was only a 1 in 32 chance that I’d hit them.

If you said there was a 3.1% chance that a gun was going to be fired in a random location on the planet and kill 10,000 people in that area, the probability of both those things happening and affecting you is negligible.

Note: I didn’t say kill.

Well then get used to this risk, because this sized rock was a once-a-century level event. You were living with this risk every year and you just didn’t know it.

One more perspective:

I didn't spend the energy stressing over the initial wave of media hype surrounding the first published probability.

A few days of waiting for rational thought to prevail helps.