Well,
to build a megastructure, you need the technology.
And: the will.
A human has a lifespan of toughly 100 years.
In the saure state our planet, more precisely mankind is: there is no damn way *we* will ever build anything that can bring humans to another star. Because the construction would take several lifespans, and every administration will either gamble to stop it, or switchest to the other extrem and supports it.
On a planet where population soon is stabilizing, is not much incentive to explore and move away.
In principle we could start populating Moon and Mars now. In far sketched theory: even terraform Mars.
So, I simply do not think that any other culture is much better in getting their internal societies streamlined and build observable mega structures, like in "The Culture". Assuming that light speed is a hard limit, there is no real incentive to leave your own solar system.
Mankind has no gene "mankind must survive". A single human has an instinct: "oh, I rather do not like to die right now!" Big difference.
When the sun goes boom, Earth is gone. And everyone who saw it coming - and will watching it - will chill by a beer.
Perhaps mankind will colonize the solar system. Far sketched. And possible but similar far sketched: travel to Alpha/Proxima Centauri. Because what makes mankind probably unique in the universe is: we have a likely habitable extra solar planet, right at our door step, at Proxima Centauri.
But we have no reason, and probably never will have: to sent probes all over our galaxy.