My grandpa did, my dad did, and I do (did).
Last year I was hunting a local park and afterwards I realized my pocket knife was gone due to a hole in my pocket. I couldn't believe it, I'm looking for stuff people lost and I went and lost something myself! I went back over all the area I'd been, but could I find that darn knife, no. Since it was a nice day and kids around, I wondered if some kid had already found it. I'd had that knife a long time (30+ years), so was sad to lose it, but guess that's how life goes.
Since then I've changed my standard routine. I still carry a pocket knife on weekends and non-flight vacations, but leave it at home if I'm going to work or functions/events where it's not likely to get used.
PS - I don't know anyone else who carries a pocket knife. Kind of shocks me as nearly every adult male I knew as a kid seemed to have one on hand at any given moment.