https://www.pcgamer.com/all-this-time-a ... ngle-typo/
That one typo cost the game developer almost certainly millions of dollars in sales. The biggest issue at launch with this game, by far, was the stupid AI. I bought it upon release because I'm a sucker for the Alien franchise and I love horror films and horror games, and it was very annoying.
Misspelling the word "tether" made a huge impact on the game itself. If you treat your day-to-day grammar and spelling as a casual "who gives a crap" thing, then it also bleeds over into your work - which for software developers, is a very bad thing.