I'm amazed that there are so many die-hard Busse fans, and this has been able to remain uncommon knowledge for so long lol.
My guess, it's not an acronym, it's an abbreviation.
INFInitely Superior Proprietary Knife Steel sounded a little too braggadocios, so Jerry being the humble master metallurgist he is decided to shorten it to something a little more mysterious
..and ISPKS didn't roll off the tongue as well.
DING DING DING, we got a winner. This is true. INFI is the crack of the knife world. Just one taste and you have to have more and we have all thought about selling our wife's wedding ring to get that grail we see listed on the forum sales site lol. It would be the most painful knife in history but it would be mine Mua ha ha ha. I digress.