Because it has a VM (portability, multiple languages interact seamlessly, bytecode manipulation at runtime, low compile times), insanely fast GC, best tools in

Because it has a VM (portability, multiple languages interact seamlessly, bytecode manipulation at runtime, low compile times), insanely fast GC, best tools in the industry (IDEs, static code analysis, debugger, libraries), and it's still fast enough to write HFT software with it. It's even possible to compile it ahead of time, making projects like a Clojure CLI scripting runtime with almost instant startup time possible (babashka).