We have some good news and some bad news. The good news is that it's entirely possible for one person to completely change the world with the power of their mind. The bad news is that it almost certainly won't be in the way they envisioned. History is full of examples of inventors who've seen their noble, genius intentions go the Frankenstein route and bring the world nothing but pain and misery, such as ...
6 Alfred Binet's IQ Test Got Hijacked by Eugenics-Obsessed Racists
The whole concept of using a simple number to score somebody's brainpower goes back to French psychologist Alfred Binet, who developed the precursor to the IQ test in 1905. It's the sort of thing that doesn't seem to have the horror potential of your average mad science experiment; Binet had merely noticed that different children of the same age learn at different rates, so why not tailor the classroom to them by putting them through a series of cognitive tests to see what they can handle?
After all, how could that information ever possibly be misused? Even if, say, children of certain races or backgrounds consistently scored lower, surely everyone would simply realize that was a sign that the system was failing them. Surely.
"What's that word you're using? You-genics? I'm afraid I'm not familiar."
Noooo! You Maniacs!
First, Binet himself knew his test wasn't all that scientific. It came with tons of disclaimers stressing that the test does not measure static intelligence and should not be used to label people in any way. And, for the single purpose of figuring out a kid's level of development, it worked pretty well. But then American eugenicists got hold of his work. The eugenicists loved the idea of intelligence tests because they wanted to use them to identify and weed out "the idiots" from the gene pool, which, by sheer coincidence, all happened to include anyone who wasn't a white American. Never mind that the score can absolutely be improved with education -- why burden the system with teaching children when we can just breed superior intelligence into them!
Thus, immigrants at Ellis Island were tested using the Binet scale (which was never meant for adults) so that eugenicists could rank races of people like they were Pokemon, but without acknowledging that they could level up with experience. The "results" naturally showed that intelligence was closely linked to how white your skin was, which was then used to propagate the idea that people from southern and eastern Europe were barely smarter than well-trained horses, and about as useful.
National Parks Service
"How good are you at pulling carts?"
It went even further downhill after Binet's invention was used to mess with people's junk. After intelligence tests took off, 30 states used them as the basis of forced sterilization, which by the 1960s affected 60,000 Americans, all because an old-timey BuzzFeed quiz determined that their Simpsons character was Ralph Wiggum.
Binet died in 1911, thankfully missing the worst of this. But not long before his death, he complained about the "brutal pessimism" of "deplorable verdicts that affirm that the intelligence of an individual is a fixed quantity." And if he wasn't such a gentleman, he probably would have added "you unbelievable assholes" to it.