Have you ever lost a domain? I haven’t despite having many domains across a number of registrars over the years. Are people just using bad registrars or what?

Yes, I have. Due to a human mistake we lost a family domain, where I hosted one of my important e-mails.

Sorry to hear that. Some registrars let you pre pay for multiple years now, it’s a good idea if you have a crucial domain that you know you will be holding onto.

Did you try to contact ICANN and explain the issue? If you could prove ownership for many years, your case would be quite strong.