That's because the shift between the V sound and the S sound is very awkward. When that kind of shift is awkward, dropping one of the sounds entirely (usually the first one) is common.
Salmon (although there are pockets of people who still pronounce the "l")
Receipt
Schedule (was originally pronounced with a "s-ch" combination, now is "sk" in America and "sh" in the UK)
There's plenty of common English words that have also changed spelling to go along with that pronunciation, though I can't recall any at the moment.
Edit: Thought of one: Donut. Yes, the "old-timey" spelling was "doughnut," and is still found in relatively common use. Long ago that "gh" in there was pronounced like a "phlegmmy 'h'." As that sound fell out of use, it eventually fell completely out of the word "donut."