I have my own domain, and I really should be using me@myowndomain but I don't. I use gmail. One reason is that so many people and services already know the gmail one so it's hard to change, but the biggest reason is that I don't trust myself nor the place where I registered for my domain to actually maintain the domain name registry and email delivery for say 10 or 20 years without any maintenance. The value of these behemoth services is that they are more or less guaranteed to be more stable than anything you can configure yourself. They are too big to fail. Even just pointing my me@myowndomain to gmail doesn't help here. It just adds a new weakest link to the chain.