Nate's Law says, "Only an idiot expects anybody to use their new language". First corollary is "All new languages are designed by idiots".
Very, very rarely, lots of people find reasons use a language designed by (such) an idiot, anyway. We are lucky when the language is not terrible, because how good it is even more rarely affects whether it will take off.
In practice, languages almost always ride to popularity on the back of something else. C rode Unix, C++ rode C, Java rode Sun Microsystems' $billions and the promise of getting off Microsoft's framework-hell treadmill, C# rode .Net, Javascript rode HTML (and then web services because the same people were coding both, at first), Go rode Google and Docker. Lua got where it is by being really easy to embed, and being simple, powerful, not weird, and (lately) fast.
Python got there mostly the hard way, but also by being easy to embed and to extend with C ABI-compatible plugins, despite being weird and extra-super-slow.
Amazon, BTW, might be unique among IT behemoths in not hustling its own walled-garden language. (Or maybe I just don't know about it.)
I think there is some concern among some people in the rust community that amazon will gain more influence over the steering of rust to guide it towards it's own walled garden.
I don't share that sentiment and I personally think that as amazon adopts rust it will gain rust community principles. But I'm probably wrong.
I don't think making a new language is so much more crazy than making any other piece of tooling. Obviously, it's going to have to have compelling advantages to convince people to move from the tools they know and love. But, if you're putting in the time, you probably imagine you have some compelling advantages. Rust is an obvious example of this, as is something like Java, or C++.
I think you're underselling Java and C++. The JVM idea is clever because it means you do all the portability stuff as part of the language, rather than asking programmers to do ifdefs for every platform. Making it a safe, memory-managed language is clever because most programmers don't care about the performance hit, but they do care about the bugs.
C++ has equally compelling advantages. If you write less code, you get less bugs, and more work done at less eyeball-hours. If you can do that 'zero-cost', with abstractions, a lot of people who care about performance are going to find that really exciting.
Rust basically continues this pattern.
Obviously you have to sort of win the lottery as well, because you need enough people to bring the language from clever-research-project to useful industrial tool, but I think the fundamental point is that successful languages have both luck, and a killer feature.
I imagine all of these languages will sink out of sight at some point, because it's just clear that as a culture we're in the very early days of living with computers, so these languages are a bit like bone needles or flint axes. I still think the innovations contained in them will go on to inform future development.
Very, very rarely, lots of people find reasons use a language designed by (such) an idiot, anyway. We are lucky when the language is not terrible, because how good it is even more rarely affects whether it will take off.
In practice, languages almost always ride to popularity on the back of something else. C rode Unix, C++ rode C, Java rode Sun Microsystems' $billions and the promise of getting off Microsoft's framework-hell treadmill, C# rode .Net, Javascript rode HTML (and then web services because the same people were coding both, at first), Go rode Google and Docker. Lua got where it is by being really easy to embed, and being simple, powerful, not weird, and (lately) fast.
Python got there mostly the hard way, but also by being easy to embed and to extend with C ABI-compatible plugins, despite being weird and extra-super-slow.
Amazon, BTW, might be unique among IT behemoths in not hustling its own walled-garden language. (Or maybe I just don't know about it.)