Yearn finance and other copycats enjoyed the hype of defi trends and got the most attention because they had low circulating supply and were destined to moon. Immediately the Defi crazy began dieing down so did they also. They got to their milestone based on hype and not because of any uniqueness of their products. Be cautious of investing in similar products with same ideology in future, as they way they got hyped up so will they crash down.
Previously we had the ICO hype, which resulted in the drastic market change of almost every project. Soon after that more than 90% got vanished out of the market. The teams made good profit and left. By the time some users benefitted, while the users who kept hold believing in the hype got fooled due to more tokens delisted.
This time we had the hype of defi. Yearn finance is one that made it known to the cryptospace, because defi isn't much into discussion. Soon after its progress it was much into discussion and people started to pour more into defi without understanding the limited supply that is making the price changes in huge margin.