A bunch of SWEs at my work use it as their primary model.

We have Claude, ChatGPT, and Cursor with essentially no cap on spend (top guy is spending over 10K a month on AI at API prices), and he hasn't had his hand slapped.

So it's not like they are using it purely because it's cheaper.

I think people like to use it for its speaking style, pretty solid performance, and its speed.