There are services that sell proxies straight from their users' machines, so the traffic looks completely normal. You can also buy a lot of phone numbers for cheap if needed, though the phone requirement is almost always circumventable if nothing else is suscpicious. As for captchas - breaking them is trivial, there are services that do it but you can also beat most/all captchas with mturk for gathering data + training an off the shelf CV model.

A social media bot army is a project that a single developer with relevant experience/time can complete on their own, providing they are willing to spend a little bit.