It’s very common for fans to travel on a tourist visa, sometimes as a guest of a con. I, for instance, had been invited to be a fan GoH at an American convention. I cannot make commitments more than a few months in advance, and even then there is a risk I have to cancel, so I regretfully declined. If I accepted such an invitation today, I could be arrested by ICE. It’s illegal to work while on a tourist visa, and accepting free room and flight counts as payment. Who knew?!
READ, especially the second link.