As mentioned above, demographics of the area you live will determine the makeup of your group. In middle and High School in the late 70s and early 80s, my gaming group consisted of all nerdy white males.
Once I got to college, I joined a role playing group that initially consisted of white males and 2 white females. Soon after I joined, 2 black males also joined. Within a year, the small group of RPG’rs had a nice mix of males and females but people of color were lacking other than the two mentioned above. It was fine. Nobody really cared one way or another. Should anyone want to join, no matter who they were, they likely would have been allowed to join. I suppose if they were somehow particularly distasteful (racist, sexist etc) they would have been shown the door. But that never happened.
The group I game with semi-frequently consists of white males and 1 white female. Occasionally the wife of one of the members of the group would sit in and play one of the NPCs.
Conventions are usually diverse. I suspect this is because people come from all over the region. I don’t think we have 50% of the gamers as females (not close really) but there is a good many there. There are varying amounts of people of all colors but, again, probably not representative of the population at large.
"Nearly all men can stand adversity, but if you want to test a man's character, give him power."