Honestly, lots of practice. I've been playing Roblox since 2008. Roblox has also always been text chat, so if I wanted to talk trash AND get kills, I had to be fast.

That + a physical inability to handwrite so I've typed virtually everything.

It's kind of useless. I almost never encounter a scenario outside of live transcription where I can conceptualize a character stream faster than my fingers can input the stream into a computer. The only programming scenario where that's an issue is LaTeX during a lecture because it's very verbose in places. I also do competitive debate which has a heavy focus on note-taking; high WPMs are useful there.

But neither of these two things will be important once I graduate university.