Make sure that even with a hacked SIM a malicious CSR can't access your account without your knowledge.
Then, people searching for things like "Microsoft tech support" would get the scammers number and call it. Google and other search engines will even pull that number from your site and handily present it to you at the top of the search results to make it appear even more legit.
Taking over unclaimed Google map listings for businesses is also really common.
Simply buying a toll free number that is close to the customer service number for a large company is bound to get you more inbound callers than you care to scam.
So no, absolutely no excuses for teaching people to share their 2fa codes.