But they sure are comforting.

Past results guarantee future results in the same circumstances. Over time, circumstances change which invalidates their value. But, in the short term, they imply a probability of future results based off of the volatility of the circumstance state.

Negative interest rates, slowing growth, models based on historical returns we'll never see again.

Not comforting at all.

Got another option?

I don't. That's why I'm worried. One of two things will happen:

1. Technology innovation velocity will increase, with the results distributed through society, driving down the cost of living (this is already happening with almost everything except real estate, healthcare, and education [1]). You won't need to invest, because it'll cost nothing to exist (let's call this "Star Trek Future").

2. Technology innovation velocity will increase, but it'll be locked up with copyright, patents, etc. Rent seeking will drive more of the population into serfdom. You will not have a pleasant life, nor will it be long (we'll call this "Elysium Future").

[1] https://www.washingtonpost.com/news/wonk/wp/2016/08/17/the-s...

I think I can tell you which of those is most likely.

I've got a child, I have to push hard for option #1, by any means necessary.