As a gardener, in my experience "volunteer" plants that randomly sprout up tend to be way more robust than the ones you plant. I believe that this is because of all the seeds that have randomly been scattered without care, the ones that manage on their own have genetics that better suit them for the environment. As a consequence, when I see a random tomato plant (or other) growing I'll usually carefully dig it up and replant it in my garden. If the plant was thriving without care, giving it just a little bit of care makes it grow even better.