I think the real question is whether the failure rate of companies using Haskell is higher than those of companies using mainstream languages.
We come across tons of others, I keep meaning to write down a list.
Not too many haskell bootcamps.
There is a need for haskell but it is not the next language to take over it is missing key features.
Which key features is Haskell missing?
The problem is the ecosystem, tooling. Lack of frameworks/crms/cmses make it a poor choice
Bootcamps try to scale the learning process. In a bootcamp someone can go from nothing to productive/professional in a few weeks. This is not possible with haskell.
I ask because I don't think Haskell is particularly lacking in this regard, and it's successfully deployed in real life software, but I might be missing something.