What makes you think we're in the later stages of the battery S-curve currently? More generally technology-wise, what makes you think energy technology in general is an S-curve? Many situations are stacked S-curves. Global energy consumption, for example, looks like an exponential (no flattening yet) [1] if you plot it starting 1800.
Also, the start of an S-curve can be described by an exponential function, right? So it is an exponential.
My point more generally was to not underestimate processes which increase exponentially. Even if they flatten at some point, they can drastically change the world and fast. For example, iPhones and computer chips took off slowly, but once they started moving they took over the world. (Or do you not have multiple smartphones and computer chips in your house right now?)
And yes your point that it's all an s-curve is theoretically correct. But I think it's a semantic discussion. Next time I'll say "never underestimate the first half of an S-curve."
[1]: https://ourworldindata.org/energy-production-consumption
