It depends on the size of your product and the amount of users requesting support. Don’t forget that the current license on the marketplace is “buy once, get lifetime support forever” which is a very very long time for that price, usually a few dollars. I’m not against customer support, not at all 
. I’ve already spent hundreds if not thousands of hours of personal support already on the forums and on my previous projects such as https://road-to-the-north.com/ which were not made to pay my rent with but it would be amazing to make plugins and games as a fulltime job, wouldn’t it?
If you are curious about my experiences, ask away! If you wonder why I am cautious about their terms and conditions which state you need to support the latest 3 major versions of the engine as a seller, then take a look at my request for LTS and why: