The reason that people try to copy the paleolithic diet is that the bones of paleoman show perfect health.
During that long period of tens of thousands of years, anyone who could not live on fat raw grass-finished meat became extinct.
There are people now who eat the same, and enjoy as close as possible to perfect health in this poisoned world.
If you give it a fair trial, it will work for you too.
Most never really try it (coconut oil! milk!), and of the few who do, most don't stick with it.
It needs a powerful incentive, like a death threat or being housebound with the worst kind of diabetes.
Thought is indeed powerful, and if you think that eating something will do you harm you are not likely to give it a fair trial.