The "popularity" of a language has to do with its utility and the availability of people to code in that language.
This is why Java and C# are so popular. They have a lower barrier to entry for doing the 80% of stuff (simple CRUD from an appropriate database) which allows for more people to get to that point. Secondly, there are well developed frameworks for supporting that 80% of stuff.
Given a database and its tables, I can go from that to being able to spin up a service that could be deployed in production in a day. Java, Spring, grab the DB driver, write the query or use some ORM to do it, build a docker image, and it's done.
A key part of that is that I can go to any company that uses a similar stack and not only be productive rapidly, but not need to relearn the language.
Likewise, I can get a person who knows that and have them up and running in the environment that my team works in fairly rapidly.
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Language Popularity and IDEs
Using Lisp isn't about using Emacs. Aside from issues of observability in non-free languages and the debugging tools, in suggesting working on Emacs, you are competing with IntelliJ and VisualStudio rather than Java and C#.
Let's look at Java IDEs for a moment. https://www.jrebel.com/blog/best-java-ide
IntelliJ 65%
Eclipse 48%
VSCode 27%
NetBeans 13%
Browser 4%
Other 2%
Emacs is a small fraction of that 2%.
Improving Emacs will not make it an environment that will compete with the others to any significant degree.
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And so, it isn't the IDE...
You could make Emacs a better environment for doing Lisp development - but that doesn't solve the problem that Lisp is too powerful.
In my days of dabbling with Lisp I found that every company that makes use of it (and even each team within a company that makes use of it) is mutually incompatible DSLs built within it.
I couldn't take what I learned and the frameworks I understood from one place and apply it to another. Yes, I could do quite a bit and understood, but the onboarding process would be much longer to learn the nuances of this codebase.
This is where Spring (in Java) excels. Yes, its boilerplate and Java is a verbose language and all the other criticisms that you may apply to it I'll let go by with "ok". But, I can go from one company to another or one team to another and be productive rapidly.
That is what makes it a popular language.
If you want to make Lisp as popular as Java, make a framework and library that is so compelling that it will have teams abandon their own DSLs for writing CRUD apps and switch to this way of doing it. Make it so that one can go from "here is an Oracle database" to "here is a docker image supplying a REST or GraphQL endpoint and the data" within a day without requiring any magical knowledge.