That's why I use a domain:
Same here. Have done that since day 1 - about 25 years ago - when I first signed up with Demon. They let you choose a subdomain name so you could have <anything>@<yourname>.demon.co.uk, with as many different things as you liked before the @.
When I had to move away from Demon, I simply registered my own domain, so I am continuing the practice.
Interestingly, in all that time, having used hundreds of different email addresses, I have only seen 4 or 5 being misused. Whether they were hacked, or sold or taken by the classic disgruntled employee, I have no way of knowing. But it's a much smaller number than I was expecting.
And yes, the bemusement when a droid registers that I have an address with their employer's name in it is usually quite amusing.
Biting the hand that feeds IT
