If we practice dilligently and gain mastery of ourselves. Thus elevating our spirit to be in harmony with the world. We have then taken the first step to helping it become a better place.
And then, we have the responsibility to teach this onto our children and spouse till they to achieve self mastery. They then should try to help others such as their friends who would then perpetuate this motion.
The best thing about aikido is you can't go around telling everyone you are a master of aikido. It isn't the kind of thing which you can brag about. People will know when you've mastered aikido. The way you carry yourself will show it. And hopefully, by becoming a good example, others will follow suit.