I'm definitely not denying that possibility, but the question is: should I trust my own very limited abilities as a hobbyist sysadmin to provide a more secure environment than what I might pay for with the likes of 1Password?

There are different risks either way. I think the specter of "it's me vs. an entire internet full of baddies" should be rightfully scary to any prospective self-hoster that takes privacy and security seriously.