18 was a long ass time ago for me. It would have been the late 90’s. The world was so much different that I don’t think anything I could say in 3 words would make any sense to my 18 year old self. I didn’t have any money at 18 so something like “buy apple stock” wouldn’t have worked.

Even taking the big assumption that I believed what I was telling my 18 year old self I can’t actually come up with anything that makes sense in context. 3 words just isn’t enough to convey anything useful given the time difference and everything else!

This map is really out of date. We now know there were humans in North America many thousands of years before “15,000 years ago”.

This is a better representation: https://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Early_migrations_mercator.svg/3840px-Early_migrations_mercator.svg.png