There would be no reason to if you are in the privileged position where cost isn't an issue.
For the rest of us something that's 95% as good for 20% the price is a hell of a value proposition.
And the price difference is far greater than $2k/month once the API cost is no longer subsidized.
Would your employer be paying an extra $20k/month to Anthropic if it can save you 2 hours a month?
Self-hosting is the biggest reason.
I think that may be part of it.
LLMs can be autonomous to an extent. All of them need steering - which is why I feel they are more a superpower the more I am an expert on the subject matter.
The more you want it to be autonomous, than yeah, you may benefit from using the very best the industry has to offer, however slightly better it is.
But if you are always in the loop anyway, you may want to try DeepSeek. You will get similar results for a fraction of the price.
Stop trying to treat these things like a replacement for yourself and instead approach them as a limitless number of offshore developers. If you are willing to be endearingly literal they will make you happy