I think that's the key also in terms of team size, if you don't have a dedicated team to take care of training / running a model then it makes sense to use an existing API and pay for it until you have enough scale.
Gemma2 might be good enough for a drop-in option as well. The benefit for those who built on ChatGPT API is that as more open weight models get released, they can silently migrate their API usage to self-hosted models … ChatGPT allowed them to prove product-market fit early!
I think that's the key also in terms of team size, if you don't have a dedicated team to take care of training / running a model then it makes sense to use an existing API and pay for it until you have enough scale.