Market Math...Flunked Again

I promised an update on math and market predictability. I've been taking CE courses for my CFP. Yes, they are annoyingly thorough. Lots of them involve using various formulae for analysing such unpredictabilities as the 'true' value of a stock, and measurement of performance.
I know it makes people feel better to think they have a clue as to the future value of a stock price, or even a hint as to the likelihood of the future value.
The common wisdom says current prices reflect investor expectations about a company's future earnings.
That seems quite ridiculous to me. The same managers do lots of math using past prices, and past earning growth, then, what? Make a pick based on future expectations?
Expectations of what? That the past will repeat? That happens only if you allow for a lot of leeway in your definition of repetition.
Microsoft, as an example was $23.40 five years ago. Today it's $24.15. In between it was $15.27 and $34.33.
Lots of people bought and sold it along the way. The net result of all that guesswork was zero. Nobody 'knew' it would rise to $34, nobody 'knew' it would shrink to $15. Please send along evidence you put actual money on the table to buy at $24, sell at $34, short, then buy back at $15. You don't have it. If I'm wrong, prove it, I'll recant.
Like 'low' PEs? During that period MSFT made scads of money, it has one of the lowest PEs around, not just in the tech sector. Right now it's under 10 times earnings.
How much do you own? Or how much are you going to buy? Money talks, bs walks. Demonstrate your belief in low PE stocks, if you have one.
This is NOT to be in any way construed as a recommendation to buy sell or hold MSFT or any other stock. We don't do that here. I use it to make a point. I could have used Berkshire. 90K 5 years ago, 116k today. Buy and hold netted you 5.25% a year, no dividend either. Did Buffett and Munger get dumb for five years?
Did you buy BRK at 90K, then sell at 148K, then short and cover at 78K, buy again? Then you made a killing percentage-wise. Except nobody did, because nobody makes those kinds of guesses repeatedly.
Even the beloved God of Stocks, Google, returned 5.2% over that time frame. Or did you presciently buy at 400, sell at 699, short, cover at 283 and buy again right away? Sure you did. Just, for the sake of accuracy, post those account statements, redact you name and account number of course, we don't want to know you that well.
You didn't? Don't feel bad, neither did anyone else.
During that same five year period, the S&P 500 (using the ETF proxy SPY) went from 125 to 130, under a 1% annual return, plus a 1 1/2% dividend give or take along the way.
This is the long way of saying, over time, you get what the market gives, no more, no less (except for the percent you give to a manager to pick stocks for you...oops.)