You can also try to build something great and end up with a shitty product or just go bankrupt. AAA gamedev is not just about wanting to make a good game and caring - it's all about production pipeline and management.
Larian grown to 450 people to build it and it's just internal staff. It's hard to imagine how many more people worked on localization, voice-over, QA / LQA and as countless contractors to on whatever aspects they couldn't do in-house. It can be very well be 1000+ people.
I not trying to say it's impossible to make good games, but making one at this scale it is literally like a rocket science.