It is something that is done by the media, both traditional and social media. Here we see the spreading or highlighting if negativity regarding a particular asset class in an effort to push it down. This is usually an intentional act orchestrated by someone who is going to profit.
FUD can also be used as a protective measure. If a certain industry is under attack, there could be an orchestrated message against the disruptive corporation or technology. A prime example of this is Tesla and electric vehicles (EVs). There are interests, such as the oil companies, who stand to lose billion in revenues from the transition to this technology. Thus, some of the public attacks on Tesla were paid by that industry.
In recent years, we saw this done to cryptocurrency, usually from people outside the industry. It stem from either a lack of knowledge to an outright agenda hoping things will fail.
The financial industry is enormous. Since blockchain technology stands to make their network of ledgers obsolete because it is superior technology, the financial institutions has a desire to hinder the progress. Blockchain can actually help out the banks if they combine TradFi with Defi. However, cryptocurrency is a problem because it provides the monetary element that makes the banks redundant. A digital wallet can serve many of the purposes that most people turn to a bank for.
Bitcoin often the main target.