There are so many possibilities with this answer, but if the goal is to make my life as advantageous as possible, I suppose I would go back to the early 90s.  I would convince my parents of certain companies and initiatives they should invest in (Microsoft, Apple, eventually Bitcoin).  There are certain women who I would react to differently just to see what a different path would look like with those individuals.  I would certainly try harder in college and explore an entirely different career path.  The possibilities are endless.

Have you ever let someone take advantage of you in a significant way?  What's the story there?