If I could learn one skill from RPG worlds, it would definitely be alchemy.
I was thinking about the form of alchemy featured in the Elder Scrolls game series. The skill would make it possible to create countless new medicines. More important, I could be able to share this skill with other people. This would lead to the creation of a separate field of science called alchemy. People would learn it in college, and after training, they would experiment and compete with each other, creating more and more effective potions. Alchemy could even be used in a power plant thanks to electricity damage and resistance to electricity.
It would also lead to some downsides. People could use alchemy to create dangerous drugs and undetectable doping substances. Alchemy would also find its use in the military, allowing the creation of real super soldiers, combining technology with magic contained in potions.
Alchemy would give hope for a better world. Potions could replace alcohol, cigarettes and drugs. Doping substances could become safe, without side effects, and allow the emergence of special sports based on doping, they would be very spectacular. That could solve the energy problem in the world. It would probably also be possible to mass-produce food in a cheaper and healthier way.
In the end, the world won't change much as alchemy spreads. While this would lead to many improvements in life, new perspectives, and a solution to today's problems, bad people would lead to much worse and more terrible results.
Would I like to live in a world where at the same time there is a cure for cancer, we live in harmony with nature and in technological prosperity, but the order could be shaken by anyone with bad intentions? Yes, because assuming that one day people would act out of pure goodness, the world would be more beautiful than it can be without alchemy.