"We definitely cannot"

Well... I really do think we could!

We have all the technology. We have power sources.

So why not? The only thing stopping us is the crazy price tag. And will power to do so.

(Note: as the decades unfold it will become easier and easier and cheaper and cheaper to do so, especially if we can get nuclear fusion mastered, then at that point it's going to happen.)

"Who does that benefit?"

Well... It benefits those who are crazy, and seeking adventure, seeking exploration, and wanting to see the expansion of Earth life out into the cosmos!

That's who!

But sure, this is NOT the type of journey for you--and that's a good thing, which means you're much more sane than someone like me!

Besides Earth is the greatest and most beautiful planet we know of in the Universe, so you'd have to be kinda nuts to want to leave this precious world of ours.

All that said, again: there's a small tiny minority of--call them crazy people, like me--that would want to do it, and wouldn't hesitate for a single instant to say no. (Just as long as my GF wants to come along with me, and I can take my cat, Lenny! Ha ha!)

And so yes: that type of journey awaits the would be crazies, like me. Probably my GF too.

But certainly not for you.

And again: that's something you should be proud of: not wanting to leave humanity's home world and cradle of civilization behind.

Also: we already know there's a very interesting terrestrial planet or two at Proxima Centauri, the closest solar system to our own.

So I mean... that kinda bodes pretty well for there being interesting planets at a lot of destinations!

Those worlds don't have to have a breathable atmosphere to be fascinating to us, and induce scientific fascination for many generations of exploration.

Plus upon arrival, the colony ship would likely fork into 2 groups: those wanting to begin building/moving on to the next solar system, and those wanting to stay and explore the planets/moons/worlds in that system.

NOTE:

Just to emphasize: an "interesting planet" does not necessarily have to mean that you can walk outside without a space suit.

That's likely NEVER going to happen, with any planet we discover.

Even if, for example, we discover a true Earth 2.0 planet, with alien jungles, forests, warm weather, 18% oxygen, etc... we would still need a space suit to walk around!

That's because that planet's amino-acid/protein patterns would likely be pretty HIGHLY toxic to us! Poison! There's hundreds of possible amino-acid and protein patterns life on Earth could have selected, and it only selected for a few of them, some likely at random.

And so even on another alien planet that should happen to have a biosphere similar to Earth (a big if)... it's likely that evolutionary pathways on that world selected different patterns than ours.

And again: those differing patterns would be very poisonous to other worlds: just simply breathing in the bacteria and pollen from such a world could kill you, and/or induce things like anaphalactic shock, and other nastiness etc... !

Anyways, as you can see this journey is NOT for most people.

So you're normal in not wanting to embark upon such a journey.