in view of what you're asking about the development of technology, and whether or not civs tend to "peak out" around our current level, i think back to the drake equation* and the coefficients for the likelihood of intelligence evolving and the likelihood of intelligent life creating technology that emits detectable signs of that civilization (space infrastructure, dyson swarms, nuclear isotopes in atmosphere , etc). Those 2 being Fi and Fc.

Id like to share whata I think is one of the cheeriest possibilities:

- that earth-like planets are rather common (we have 3 such planets in the Sol system),

- basic life is less common but still pretty common (decent chance mars could have had life, maybe europa's sub-ice oceans has it now... conceivable at least),

- but what isnt super common is the development of human-level intelligence, and even less common is developing technology to the point we are currently at

- but (and this is the most cheery part) even though human-level intelligence and our current tech level is very uncommon, that once a species develops that level of tech, barring a catastrophic extinction event (DNA-hyper-plauge, mega-asteroid, all the nukes getting launched at once), that that life is likely to continue for a long time.

I say that last part because even with our current problems with the Anthropocene extinction and climate degradation, it's likely that humans will be here in 100 or 1,000 or 10,000 years.

Worst case could be even be so bad as humanity entering its first ever world-wide dark age (as opposed to regional dark ages) where higher technology is less prolific and more concentrated. Even given something like that that - which i think is neither a certainty or even a reasonable conception of the future - humanity would continue and 10 generations on our decedents would start something akin to a second Renaissance.

So what I'm getting at is once a civilization develops roughly our level of technology, it may be very durable even in the face of temporary disasters and darkness.

Now, as far as the fancy space tech you bring up, yeah, who knows... It seems like those tech have a big issue beyond Physics, which is the Fermi Paradox.

If say, Dyson Swarms were "possible" (they really seem like they should be... we could start building one now), then we should be seeing evidence of that all over the universe from those civs who've come before us and build them. That's scary to think about, that maybe we're the first life to get to this level in the universe. Then again, maybe advanced civs learn early to obfuscate the signs of their existence, or perhaps even use technology that we don't recognize / cant detect.

A great Youtuber named Isaac Arthur talks about both the drake equation and the futurist's existential bummer about the Fermi Paradox. Check him out if anything i bring up here sounds cool.

*Drake Equation is a simple(ish) way of plotting out how likely / many adv civs are out there based on the likleyhood of some conditions. From wiki -
The Drake equation is:

N = R ∗ ⋅ f p ⋅ n e ⋅ f l ⋅ f i ⋅ f c ⋅ L

where:

N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past light cone);

and

R∗ = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space[

https://en.wikipedia.org/wiki/Drake_equation