Right now, fundamental would have helped you to realize that bitcoin could have gone down whereas TA wouldn't help you to realize that, there was too much things showing that bitcoin could be going up, even the most advanced trader was saying that $12k was a wall that we are trying to knock down and that wall can't handle to stay up forever so one day we will go up, that was the logic for a long time.
Unfortunately they were wrong, but if you worked with Fundamental instead, you could have seen that it is actually doing not that great, not as great as TA shows, there was too much pressure. All those times we tried to go over $12k and didn't? That means someone didn't want it, and buyers are not going to just keep on buying from that level to make people richer so it went down.
How would fundamentals have predicted anything? Fundamentals have very little to do with short term price action. That's why it's so commonly said that markets are irrational.
You raise a good point about trader sentiment. I'm really big on contrarian trading. When everyone is thinking the same thing, the opposite usually happens. Next time it seems like all the traders are planning on BTC going to the moon, consider trading against them.
What many people don't realize is that being a good trader is all about reacting to price action, not predicting it. When we were trading at $12K, predicting whether bulls would fail or not was a gamble. Stop selling below the $11,100-$11,200 breakout zone was much more of a sure thing.