You are given an opportunity to hard reset our universe (particularly, the Earth). You are also allowed to change one rule about the new universe. What rule would you change?
The rule could be anything, as funny or as serious as you want. The universe will progress in a similar way that it has up until this point, unless your changed rule prevented it from doing so.
Some examples might be:
The invention of currency is not allowed.
Iron is slightly less stable.
The Ancient Greeks are able to cultivate Silphium, which does not go extinct now.
If you don't intend to cheat anyone, the party you're interacting with gains in a similar "amount" as you
If you achieve personal gain at the cost of someone else, their net gain will be even greater than yours
In case there's no direct party you're interacting with while gaining (such as you running a red light when no one's around to be inconvenienced), society as a whole gains