My 30th is soonish--not this year. I can't imagine doing Zoom with the group of them, though I went in person to the 10th and 20th. For the latter, about 25% of a class of ~450 showed up--not bad--and I remembered most of their names. I think it can help to have at least one amiable contact present; a friend and I wandered around together, which made it easier for people to get their "How are those nerds doing" remarks out faster as well as easier for us to turn the conversation to something more sensible.