Here's how it works.

Pretty much everyone will have had one or more of their passwords leaked at some point (check at https://haveibeenpwned.com/). So scammers can grab a password and send an email like the one you received. People see there's a genuine (if old or unused) password in the email and that makes them think the rest of the email is real. It's not (as you obviously know as you haven't been doing what the email says you've been doing).

I get email like this pretty much every day. It's completely safe to ignore them.

But please don't react in the way you do. At best you're just adding to the amount of pointless email sloshing around the internet. At worst, the burner account that the scammer used actually belongs to some innocent bystander and they're now getting the spam that you signed them up for. There is almost no chance that the scammer will even see the spam that you're sending.