What happened to me is that I went to reset my password one day, and they required I confirm my backup email which I no longer had access to.
Even though I had access to read messages sent to the gmail account itself, and I had access to the phone number connected to my gmail account, without my backup email as well, I could not get anywhere. The recovery procedure that asks you questions didn't get me anywhere either, because I couldn't possibly answer things like exactly when I started using gmail due to using it for too long. And I even had an archive of a few years of my email, that ought to have enabled me to answer the other questions, but it didn't work and there is no feedback nor escalation procedure.
I may well still be logged in due to a certain buggy/obsolete device I have; I think it's probably been five years, but I don't believe I will ever be able to log in or reset my password again.
It didn't have a great deal of impact on my life in the sense that I was able to simply switch to a new email account, but I feel a certain sense of loss at not being able to use the one and only address that was my full name. More significantly, it indelibly engraved in my mind, the kafkaesque, diabolical nature of Google, the ingrained lack of customer service, the way in which, while they may mostly be geniuses, when they screw up, they won't admit it and there's no appeal.
The thing that I object to on an emotional and logical level, is that adding a backup authentication method removed the ability to use the primary authentication methods. If I just never added the backup email I'd be fine! I can't accept that makes sense, that it adds security. Something the user does to make them safer should not make them less safe.