Colonization includes expansion.

For now assume that all the carbon, nitrogen, and oxygen you want is available in the atmosphere and solar power. You still need hydrogen to make plastics, and you are going to need silicon to build more solar panels, and you need metals you can forge. The surface of Venus is 50km below, which isn't as far away as the ISS, but it's still 50km straight down and then back up for anything.

It might be a nice vacation spot, or a penal colony.

There is work being done to replace silicon with graphene. It's of course a long shot, but would make this a lot more feasible if possible.

For hydrogen, you have sulfuric acid.