You are right one reason for OPSEC. There are plenty of people who a trustworthy enough under normal day to day situations that would quickly and with no thought cut your throat just as fast as any street thug during SHTF. I’ve see them even here on FR boasting about how they don’t prep other than guns and ammo, which they will use to take what they need. Almost as worse are the scoffers who make fun of preppers, but when the SHTF they will be the first to run to them and they will have the need to punish those who prep for proving them wrong. They will also be among the first to run to the Authorities to report your preps.
Servicemen are bad enough in normal times. Not that I have anything of value (really, I don’t) but what I do have is mine and I don’t want to come in one day and find out a guy I paid to fix the basement furnace came back with his buddies and absconded with half my stuff. Many preppers store their supplies in the basement where these guys may be unsupervised. It would be wise to partition off the utilities from your storage area.