Aye, this! Redundancy of species...
As in sending a part of species to a hostile place where all living is confined into a one big life support machine, without fresh air (which is very different from freshly uncanned or chemically generated air), without fresh and varied food (which is very different from artificially grown), without open sky and Sun above, without seas, rivers, forests, mountains, without anywhere to wander to find inner peace, in a setting for a psychologic horror where one deranged member of expedition is enough to bring it down.
That is going to contribute so greatly to the redundancy of our species.
I'd much rather be on a cruise ship than a lifeboat, but that doesn't mean cruise ships shouldn't have lifeboats.
No serious advocate of settling Mars, Venus or anywhere else in space seriously believes it will be easier than remaining on Earth, nor are they suggesting that it means we can abandon the Earth entirely, or care less about protecting its biosphere. They simply understand that, no matter much of a relative paradise the Earth is, so long as 100% of humanity exists there then we are placing all our species' eggs at the bottom of a single basket's gravity-well. It will do us absolutely no good if we solve climate change, war, poverty, disease, etc. only to get wiped out by the next comet or mega-asteroid that smashes into us. And, statistically, eventually one will.
>As in sending a part of species to a hostile place where all living is confined into a one big life support machine
At first, I thought you were describing the settling of Australia
Got a better alternative?
This puts the cart before the horse. At least one important question to answer before. Does something absolutely needs to be done? Then we start looking into the best alternative.
What's the concrete threat scenario you avoid by moving to the Venusian clouds? Global warming? Fix it on Earth and if you can't convince people to agree on a solution here, how will you convince them that a Venusian balloon is the best way forward? Nuclear annihilation? Probably digging deep underground is better. Total planetary annihilation? Maybe stations in Earth orbit, or Moon's poles, or L point, etc.
Are we looking for options for which we have the technology and capabilities today, or a few centuries from now? That changes your options from "balloon on Venus" to "terraforming Venus".
The engineering and other practical considerations needed to get such a "station" a realistic chance at long term survival are about as sci-fi for us today as the starship Enterprise. We aren't even at the point where we can sustain an isolated Earth based colony indefinitely in an inhospitable environment. They all need constant maintenance and resupply from the the hospitable environment just a stone's throw away.