Java WAS slow in 1995, when there was no JIT etc.
Java CAN be insecure IF you use an older version AND your code exposes some vulnerability.
But non-Java games are insecure as well… simply nobody cares. Oh, and don’t let me get started on the DRM rootkits that are installed without the user knowing, which are way more likely to cause actual harm to users…
But back to the point.
As others pointed out, bundling everything on a .exe has many disadvantages.
Obfuscation and assets protection are m00t points.
Most importantly, we are in 2017. Installers are old school, today there is steam that takes cares of everything and you don’t even bother clicking on the executable, as you run stuff from the steam client. Other “app stores” works the same way.
If I want to distribute stuff outside of the market, I just zip everything as I personally prefer it over installer…