Learning the big ideas in all the large disciplines/fields of science!

You don't have to get four graduate degrees. Just go on sites like khanacademy and buy some books and learn the large ideas.

How many people misunderstood evolution? (I certainly did, I was taught it all wrong in school). And how many people lack a basic introduction into statistics and probability that would make them able to make much better judgements? You don't have to get a PhD in psychology, but imagine how much better the world could be if everyone was at least aware of Kahneman/Tversky and Milgram. You could go down the list. Almost every field has something useful to offer, and you usually don't have to go very deep to understand it!

People make bad/immoral decisions and self destruct/hurt others all the time just from basic ignorance. Not out of malice or stupidity, just because they didn't know something that they could have easily learned. It's a very simple mistake to rectify. Again, I'm not arguing you should know everything (I certainly don't, look at my name), and none of us are ever going to learn 1% of all the things there are out there to know. But the amount of time it takes to learn these things dwarfs in comparison to the huge benefit of knowing them.