I hate to break it to you, but we have already dammed most of the rivers. Any beaver who thinks that there are no dams around is just one that hasn’t tried to swim far downstream :)

The argument is really more why is there only one technological species on the planet - the answer is the first one to arise will displace all the other potential competitors. This is exactly what has happened on Earth and why any other species that has a chance of creating a technological civilisation is not doing so well.

The same argument applies to the universe where the first civilisation that chooses to take over the universe will displace any competitors that choose not to. All it takes is one civilisation to spread and the whole universe goes dark.

Population of apes on Earth:

     Orang-Utan: 50,000
     Chimpanzee: 200,000
     Bonobo: 35,000
     Homo Neandertalensis: 0
     Homo Habilis: 0
     Gorilla: 100,000
     Homo Sapiens: 7,500,000,000

Yup. "The first civilisation that chooses to take over the universe will displace any competitors that choose not to."

How many zeros would you need to use to count the ants in the world?

I'd look at ant species rather than ants.

Note that ants don't directly compete for a niche with humans.

And megacolony species such as the Argentine ant are displacing other ant species.

No species the size of ants can ever smelt steel. They are not competitors for humans to become Earth's technological primary species.

Have you read City? (Not that it's seriously making an argument the other way.)

Arguing that smelting steel is the key thing is the typical, we're good at this therefore this is what matters argument we've been making since time immemorial.

Humans can't sneak into other organism's bodies and take over their DNA (yet, to be sure) but viruses can, so humans just don't have a real shot.

1. Ants are not, technically, apes.

2. Ant biomass is about the same as human biomass on Earth.

3. Typical human mass is 60kg, typical ant mass is 3mg.

4. Do the math.

Just one zero who makes many appearances.

No, for power we only bother to dam huge ones which no beaver could possibly take on.

Exactly. I like this analogy especially because our needs as a more advanced civilization are drastically different from the function performed by beaver dams. It's not even about energy per se. We could dam all the streams, but that's not a meaningful pursuit given our interests. Likewise, wondering about damming all the stars assumes that solar energy requirements are both the bottleneck and the ultimate purpose of advanced civilizations.

Live in the universe is necessarily finite, because the useable negentropy is finite. It is a plausible assumption that an advanced race would want to keep on living as long as possible. This means managing the negentropy as well as possible, which means dismantling stars and using them. So unless you disagree with my assumption, or add magical energy sources outside of known physics, starlight seems to indicate that there is no race capable of harnessing all available energy.

"We could dam all the streams, but that's not a meaningful pursuit given our interests"

Could you please explain that to the World Bank and governments in Africa, SE Asia, China, and Oceania that insist on damning the last free-flowing rivers on Earth?

Rivers are bigger than streams.

When it comes to hydroelectric power and titanic concrete structures, we look for very different water-situations than beavers do.

Humans dam lots of small streams too for agricultural and recreational uses. They don't get much news, but if you look at aerial surveys of places where people live you will see lots of small dams.

But now you're hypothesizing Aliens + some extremely convenient energy source.

In order to justify ignoring all the burning stars, it needs to be easier to tap than solar and much much more energy than all the stars will ever generate. I think that requires new physics.

Really the energy source must be infinite. If you can see that it will run out in a trillion years and you can survive for another billion by harvesting suns, somebody will.

We have nuclear power but still dam rivers, and I think beavers notice.

OTOH If there is a source of unlimited free energy, maybe some of those bright spots in space aren't stars at all.

Aren't you hypothesizing aliens + making human whims seem like universal goals? I don't think there needs to be an easier source of energy than solar to justify not tapping stars, just lack of desire.

This is kind of like how we currently have 8tb drives, but many systems are shipping with 128 or 256gb drives. In that case, the trade-off is for the speed of SSDs.

Or lack of ability if FTL is completely impossible relativity puts a limit on the size of a civilization. And the universe can easily out a time limit on it as well because extinction events can happen.

Even if we move onto mars a GRB would cook all of us.

And even if it's something considerably more boring then expanding to other planets or even star systems might not save a civilization from collapsing.

Or dammed a few stars and decided it was ugly? Maybe watching other life emerge is their version of national parks?