Here are some facts that many people don't realize when they get insurance. Some were already mentioned above.
(1) Not all coverage is what you think it is. The OP mentioned how they value the car at $500. That's based on the language in the insurance contract. Many people get "stated value." Top level historic car insurance is "agreed value." You want agreed value. That means you agree your car is worth $X, and if there is a claim, that's what they pay you (subject to deductibles and some charges). But "stated value" just means you said your car is worth $X, they did not agree to it, but they are going to charge you for insurance as if that is the value of the car. But the policy usually has language that says even though you stated the value, the value is still the same equation that basic coverage has - i.e., the $500 mentioned above.
(2) Many of the policies say you have ZERO coverage for someone driving under 25. I share my hobby with my kids. That means I can't have them drive or drive with no coverage. That's a no go for me. Life's too short.
(3) Some of the policies require you to have a new car that is newer than 15 years old. At one point, my newest car was my 2000 Boxster S. Great car. But I couldn't get classic insurance from some of the carriers at the time.
(4) As indicated, many of the policies do not cover driving to work. My friend with an XK140 drives his car to work and says if anything happens, he'll just tell the insurance company he was going to his mechanics'. Personally, I do not want to rely on fraud for my coverage.
(5) One of the classic policy companies told me they would not cover me if I used it to go to the hardware store. Well, on weekends, when I go on a joy ride, there's a pretty good chance I might need to stop at a hardware store to deal with my Honey Dos once I get back from disappearing.
So on some of my cars, I know I'm underinsured. But I'd rather be underinsured than not insured - and I take super care to self insure based on where I drive, where I park, and keeping my eye on my car.