Another reason for their usage of the JVM could be because a lot of these languages specifically designed for concurrent programming either didn't exist or were

Another reason for their usage of the JVM could be because a lot of these languages specifically designed for concurrent programming either didn't exist or were in their infancy of real-world usage. Erlang was proprietary until 1998, and Haskell was not created by a large company. In the meantime, Sun was pushing Java everywhere they possibly could. So it makes sense that larger tech and financial firms, especially those who established themselves in the late 1990s (or descendants of such companies), would use the Java platform. There were also a lot more Java developers than Haskell developers, and there still are, and that's a big part of the decision-making process when choosing a platform.