I'd recommend waiting a while and keeping an eye on it. Is there are redness or swelling around the gums? If not, then the cat is probably not even feeling anything. Obviously, if there is infection present, then you'd need to do something right away. My sister has had a loose molar for 40 years and no problems.
I agree that vets (like any other business person) will try to sell additional services. But you also don't want your pet to be in pain.
My cat is now 16 years old and in perfect health. But, she's NEVER had "people" food and always eats dry cat food and fresh water daily.