The weaker version of pure reward optimization in humans is basically just the obesity issue, and the biggest reason humans became more obese on a population level in the 20th and 21st century is because we have figured out how to goodhart human reward models in the domain of food such that sugary, fatty and high-calorie foods (with the high-calorie part being most important for obesity) are very, very highly rewarding to at least part of our brains.
Essentially everything has gotten more palatable and rewarding to eat than pre-20th century food.
And as you say, part of the issue is that drugs are very crippling for capabilities, whereas reward functions for AIs that are optimized will have much less of this issue, and optimizing the reward function likely makes AIs more capable.
The weaker version of pure reward optimization in humans is basically just the obesity issue, and the biggest reason humans became more obese on a population level in the 20th and 21st century is because we have figured out how to goodhart human reward models in the domain of food such that sugary, fatty and high-calorie foods (with the high-calorie part being most important for obesity) are very, very highly rewarding to at least part of our brains.
Essentially everything has gotten more palatable and rewarding to eat than pre-20th century food.
And as you say, part of the issue is that drugs are very crippling for capabilities, whereas reward functions for AIs that are optimized will have much less of this issue, and optimizing the reward function likely makes AIs more capable.