Personally, I'm more comfortable with a service that has entire teams whose entire job is finding and fixing holes in the service than I am with something I toss on a server somewhere and forget about for months at a time.

Realistically, which is more likely? 1) That 1Password gets breached and loses their customer information, or 2) that I install Bitwarden on my server, somebody discovers a hole in it, I don't hear about it for a while (or do but don't have time to update), and get all my passwords stolen?

For me, the second seems more likely, so I'm happy to stick with 1Password.