Well yeah, I mean, it's basically like wild price swings. If Bitcoin can go from $6,000 to $20,000 to a few weeks, it could go from $20,000 to $6,000 in a few weeks. Similarly, public opinion can go from "it's dead" to "omg it's the future" at a moment's notice. Bitcoin price is volatile, so it's just natural that public perception towards its future is also volatile.
have you ever thought that it is possible that what you hear online is not exactly what "people" think and more like what they advertise publicly?
for example when the price is falling and traders have switched strategy from buying to shorting, they obviously want the price to drop more so they can make more profit. many will start talking about doomsday so that maybe the price goes lower and they make a little bit more profit.
the opposite is true about rises.
how effective this bullshit is, i have no clue but this is what's happening!
I have zero doubts that this is happening, but I'm pretty sure a good chunk is also genuine fear for losing their investments and/or excitement over doubling their money. I'd say it's very effective, because it gets weak hands to buy in and then dump in a hurry. The people who get swayed are always the losers.