Same here. I've had my gmail address since 2004. What's scary is all of the services you can sign up for that DON'T require email verification. Early on I struggled with a large bank for two months and finally gave up. I still get statements and could theoretically change the password to login (but don't). Most recently an attorney sent me confidential information. That one was interesting, they tried to threaten me for intercepting the email. That one I actually took the time to explain but most I don't. I have dealt with two dating websites as well. With those, the only way out was to request a password change and reset the account information to a gibberish email address making the accounts inaccessible.
It has gotten better over the years because a few of these folks had family members send them email and I was able to get them to contact the person trying to use my gmail address. As far as I can tell there are about 5 others that thought they had my email address. Only one contacted me directly, they asked me if I would just give them the email address. I told them they could buy it from me. They offered $10, I countered with $5,000. That ended that.
These days when I have the time I will unsubscribe but those companies that don't have the option, I check the website for fraud or IT contact info and send one email. If I don't hear back, I report them as spam.
Again, it has gotten better over the years (I've been dealing with it for over 10). I'd like to believe some of them realize they aren't getting email and finally fix it. The dating websites... at least one of those didn't even have the same name (or any connection) so I think they were just giving a random email address (whether it was to start a new trial or whatever). But it seems to be the price you have to pay for as an early adopter to gmail. I'd be interested to see if anyone else can come up with a better solution (short of getting rid of it).