Warm blooded systems though can power high energy activities like maintaining a large brain, which could figure out how to get warm.

A few degrees can kill a human only in theory, in practice a human would wear a jacket or seek shade.

Octopi are cold blooded and smart

But they live in a fairly constant temperature environment compared to a land reptile for example.

Update: they do some funky stuff https://www.sciencedaily.com/releases/2023/06/230608120915.h...

> The octopuses achieve this by editing their RNA, the messenger molecule between DNA and proteins.

Lesson number two: if you cannot avoid dealing with multiple states, consider monkey patching. The result might resemble an eldritch horror, but at least it will work.

No wonder they die so young

A few degrees kills many, many people every year. I didn't say a few environmental degrees, I said a few degrees of regulated temperature. All it takes is a tiny little virus to make your immune system eat itself and kill you with your own heat. That's a very good example of a system that is highly reliant on the right environment to operate properly.