The more complicated version of this is "if drugs were an improvement to our overall evolutionary fitness, we'd have evolved to do what the drug does by default". This opens up interesting avenues of thought, because some drugs aren't an improvement to fitness in the ancestral environment.
Stimulants usually make you burn more energy, so they're fertile ground now that calories are cheap. Dietary energy has only been affordable for a couple of centuries, so there's not a lot of time to have evolved more wasteful bodies and minds.
This. If the reward cycle for a hyper brain was shorter, we would all be genius mental colibris, but then easily exhausted to tupor and would have these debates over stimulants to extend the hyper or reduce byproducts of accelarated "normal" consciousness.
There isn't one when it comes to coffee, though I accept your fundamental premise that "no free lunch" isn't always true.
Coffee may be good for your healthspan but addiction to caffeine is real and you lose the nootropic benefits if you hit it every day, as most coffee drinkers do. In fact, it's worse than this, because your brain performs worse before it gets its coffee, at which point a daily drinker will just arrive back to baseline performance. Not to mention the irritation, "don't talk to me before my coffee", etc. that other people have to deal with before you get your fix. Or the hit to your wallet whenever you purchase coffee from your local barista.
I want to be clear I'm not throwing shade on the other healthspan benefits of coffee that do come from daily drinking but pretending coffee is a free lunch is naive.
Before I switched to drinking coffee, I used to drink carbonated caffeinated beverages like Coke and Pepsi. Up to twelve per day. I'm convinced that is what gave me diabetes. So, I switched to Diet Coke. But then I learned about all the bad chemicals in Diet Coke and Coke Zero, so I switched to coffee.
I drank caffeinated coffee for a long time. Decades. Occasionally, I would get to a state where if I had too much coffee, I would get caffeine headaches. And if I didn't drink enough coffee, I would get caffeine headaches. And there was no gap between those two states. I'd have to completely decaffeinate for a while, before I could reset my system.
A few years ago, I switched to cold brew coffee, because it has about 70% less acid than hot brew. That was much better for my stomach.
Then about a year ago, I switched to decaf cold brew, because the caffeine was causing too many problems with my heart rate, and my four different blood pressure medications weren't able to keep me in a good enough state.
So, I stopped drinking coffee altogether. Now, it's just plain water. And I do feel a lot better. No heart rate problems, no excess acid, etc....
Stimulants usually make you burn more energy, so they're fertile ground now that calories are cheap. Dietary energy has only been affordable for a couple of centuries, so there's not a lot of time to have evolved more wasteful bodies and minds.