...Yes And you can't have a position in the market that you wish to enter. Only an opinion that you wish to turn into a position, and again, Yes, you would care about the prior pattern before entering. Otherwise, lets just blindly by anything and everything NOW, NOW, NOW. Oh wait, that's what the ETFs are for.
When I traded stock, the flag pattern was my favorite setup. So much so that when my future ex-wife offered to knit a sweater for me I had her embroider a flag pattern. Maybe it's not the most stylish sweater around, but it makes for a good conversation piece!! Your main concern should be if the flag pattern will work or not. Now, I can tell you that it is the most dependable of all chart patterns IMHO, but, of course, provided that it is an actual flag and not some way out on the limb price movement that someone imagines to be a flag. And from what I've seen, that makes up the vast majority of the cases. Patterns develop according to changes in supply and demand. They need not be created deliberately. And, according to your question, if you think people who exit during a flag are dumb, remember that 99.9% of traders and investors can't recognize even a picture perfect flag pattern, or any other pattern for that matter!
It could just be a random pattern that occured spontaneously, or it could be a hoax created by the baker to increase the perceived value of a piece of bread
Give enough numeric data and humans can draw patterns out of anything. Look up charts of random number generated "prices". No one can tell the difference between it and actual prices charts.
Bulkowski ranks it #1 so I'd say you were on to a good thing there. http://thepatternsite.com/htf.html
It's NOT deliberate. Thus, a bunch of institutional traders aren't talking on the telephone, instant messaging and saying to each other..."lets buy/sell the price action at specific prices to form XYZ pattern". Yet, its well known that some institutional traders have conspired to control price movement in certain markets. That's illegal and many times they are caught. For example @ https://www.theguardian.com/business/2012/dec/11/libor-investigation-three-arrested Yet, they weren't trying to form some XYZ pattern on a chart. In contrast, instead of saying flag patterns...some institutional traders have illegally manipulated prices into moving Up or Down and any kind'uv specific price pattern or multiple patterns is just the result of someone's "perception" of the market. Kind'uv reminds me of my kids and me looking at a cloud in the sky. I say the cloud looks like a horse, one of my kids thinks its Zoro's Z mark and my other kid says its a fireman with a water hose. Simply, that flag pattern that you see...others see something else (bullish, bearish or nothing) even though you all are looking at the same price action. That's why some say trading is part art and part science.