I sympathize with your comment. It's the 'little Swedish words' that give me the most frustration. I have tried to find a reference that provides a comprehensive explanation of the circumstances in which one uses i, på, till, etc. but have been unsuccessful so far. I guess this means we must learn by our errors and when someone says 'that's just the way we do it in Swedish' I have to put on my zen hat and move on rather than venting my frustration and risking getting downvotes. Good luck, John.
The word actually did use a soft k originally, or at least its origins did, as it comes from killing (meaning "kid" as in "goat offspring"). It likely changed to a hard k since it's onomatopoetic. Other common words that went through this are e.g. kissa, as bynny2015 mentioned above, and kisse (meaning "cat") - from the sound one might make to call on a cat: kss kss kss!