I personally like both languages and think they both have a place. My 2 cents.
The JVM works exceptionally well when you are dealing with long lived apps which deal with a lot of allocations and the machine running it has a substantial amount of memory. Things like webservers, for example, are near perfect fits for the JVM.
Rust does really well when you need high performance, low memory, and ultra fast startup times. It won't necessarily outperform the JVM when you talk about doing a lot of heap allocations (due to heap fragmentation) and it unfortunately suffers from the same heap fragmentation if you are dealing with a long lived server that does a lot of allocations. But then, maybe that performance loss is acceptable for the ability to very quickly scale up and down servers.
Now, the JVM is making great strides towards getting faster startup times and even fast performance at startup (AppCDS). However, those strides often involve trade offs with either build complexity or performance losses (such as Graal's AOT). The benefit for rust is that it is as fast as it ever will be without any special build steps or tweaks.
Oh, and let's not forget diagnostics. Flight recorder for the JVM is simply AMAZING. The ability to hook up to a poorly behaving production server, start flight recording, and getting detailed information about things like "where are allocations happening" or "what are the hot methods" is simply amazing. No other platform that I know of has the level of detail you can get right out of the box with flight recorder. Certainly not without restarting the application with additional configuration. For example, you'd need a special build of rust with profiling turned on to even start to get the same level of info, doing such also significantly negatively impacts performance.
