Oh God! More than half a million USD worth of Bitcoin lost. Are you sure that it was a keylogger? I am confused. How did they managed to install the keylogger in your desktop? Or are you using a computer in a public place such as library or college? It was much better to purchase a hardware wallet such as Trezor and Ledger and keep the coins in them. Anyway... don't lose heart.
Probably downloaded something suspicious to visited a website with javascript enabled. It's so easily done but so easily avoided at the same time.
Even I have java script enabled in my browser. Is it that much of an issue? Without Java, we can't play most of the videos and animations. Even the YouTube videos will not play properly without Java. Is there any solution for this? And BTW, if I have Kasper in my system won't it block such spyware and trojans?