You mean CO2 and small amounts of nitrogen?
That doesn't seem like a great resource. If you value CO2 so highly there is plenty right here on earth that nobody wants and people will actually pay you to remove from the atmosphere. No need to go all the way to Venus.
Even on the surface of Venus, inhospitality notwithstanding, the resources are at the bottom of a gravity well equal to earth's. It is way more viable to mine asteroids than mine a planet, especially a planet like Venus.
Mining other planets is only interesting if the market for the resource is on that same planet, or we've exhausted the supply of asteroids with that resource.
Critically, it gains us raw materials. Space is empty. The upper atmosphere of Venus is full of elements we can use to sustain life.