"And you think that's what a GOOD investment looks like? How much inflation do you expect over those 18 years? How many black swans?"
Over the long term, inflation won't be an issue. The cans of Coke, the McDonalds Cheeseburgers, can be reliably expected to increase in price along with inflation.
As for black swans - the GFC was supposedly a once in a lifetime black swan, yet it's barely made a dent in the relentless growth in sales of the major blue chips. People on the streets, they're still buying coke regardless of what wall street does.
You may think that getting a high quality company like the Coca Cola Company for free after 18 years is not a good investment - but by selling your stocks and staying in cash, now that's a bad investment. Not only will it take more than 18 years to get your money back in a term deposit - assuming the cash rate goes back up to 4% - in cash, inflation does matter. That 4% interest is nominal rather than a real rate of return you'd get with stocks.
I mean, 18 times is not ultra cheap - the stock market can for all I know fall by 25% and take the PE to 13.5. Knowing the irrationality of the markets, I think this may well happen. But that doesn't mean 18 times isn't a good investment. IT just means 18 times is good, and 13.5 times is even better.
You will do well over the long term buying at current valuations, and you'll do even better buying at lower valuations.