You could throw away a few thousand coins at provoking a plunge but if the price goes down and stays down then that's looking like the 'true' price to me. No one can keep a price down for more than a few hours artificially.
there was the bitstamp bearwhale back in 2014. i think that wall took a few days to break.
i agree though. i might give it a day or so to account for banking delays, but if real people are buying/selling a price level for any sustained period of time, that's the real price. that's why i don't buy the BS about willy bots and tether printing either. sure, maybe there were efforts made to pump the price. you think those alone could sustain bubbles (with full-fledged media coverage) for months and months? of course not. real money did that
There's more to it than you think
If it was real money that made the price rise from zero to hero and all the way up to almost 20k (within just one year), then where did that money go? As a conspiracy theory, let's recall that in August 2016 Bitfinex was hacked with over 120k bitcoins stolen. So how could they repay that debt? After they redeemed all BFX tokens in early 2017, they started to run "quantitative easings" with Tether, which allowed them to buy up real bitcoins with fake dollars and close the liquidity gap after the token redemption. That made Bitcoin go parabolic. Then they stopped printing tethers and the price expectedly crashed. It is basically the same thing as with Mt. Gox but done right this time