I remember a few decades ago somebody saying the JVM was incredible technology, and as a user and programmer I still have zero clue what the hell they could have been thinking was good about the JVM.
I hear that now, decades into Java, they have figured out how to launch a program without slowing a computer down for 10+ seconds, but I'll be damned if I find out. There are still so many rough edges that they never even bothered to try to fix about launching a .jar with classpath dependencies. What a mess!