You're talking like we're gonna be building a Dyson sphere (or swarm) in the next 20 years?

Hardly. We have plenty of time for that, there's no rush.

Or colonize outer planets? It's science fiction...at least for next few 100 years.

Again, a few hundred years is nothing. The sun won't become problematic for a few hundred million years.

We can't rely on a deus ex machina save.

Things like Dyson swarms and star lifting are not "deus ex machina", they're scientifically rigorous proposals.

if we aren't strong enough for that, I don't think we're getting anywhere near K-II.

Getting to K-II means not needing the planet we evolved to live on.