Not just the cost, also boredom. I have used AI to trace down some tricky multi-threaded issues (someone has to write that cross thread framework, and it was me - fortunately most of our code isn't this complex). I already knew the code well, but it would have taken me a long time to find the same issue - the more likely thing is I would give up. Even if I don't give up I'm likely to get bored/frustrated. A month worth of tokens replaced what I would have needed a year to do if I was allowed to spend a year on it.