Pretty much. I already use my own domain for my main personal and business email addresses and I've also set up email addresses for several family members on that domain. So, if I moved to a paid plan, I'd not just be paying for one email address but about 8 or 9 --either that or face the unpleasant task of explaining to family members that they now needed to pay to continue using the email addresses they've had for years.

I also have a few other domains that only I have email addresses on and I run the email for those through Gmail and Yandex Mail's servers.

I've also got a few other email addresses @gmail.com and @yandex.com which I use for less important stuff like signing up for forums / websites and the like. So, I wouldn't want to be replacing them with a paid plan either --given they're not used for anything important.

So in essence, "free" [and reliable] is more important than "secure". I'm not majorly unhappy with my current setup, but I'm always open for giving rival services a try out, just to chip away at the stranglehold the big boys have on the market.