I was at PAX East over the weekend with a 100,000 strong cohort of people who aren't exactly well known for personal hygiene and I wasn't scared, but it probably wasn't the ideal place to go. As long as you take strong precautions (cleaning shared surfaces aggressively, using hand sanitizer or washing hands after touching shared surfaces or people, avoiding sick people, avoiding confined spaces, etc) then I don't think there is really that much risk short of being coughed on by someone, but not much risk != basically no risk if you don't go. I actually went with a friend who was sick with the common cold and I was more concerned about him getting me sick than me getting COVID-19, and it seems I managed to avoid both.