The issue here is you have to think about others. Not wearing a mask means there's a higher chance of you catching the virus (especially when you're around others not wearing a mask as well). Of course you may be asymptomatic which means now you can unknowingly pass it on to others who are at higher risk for example
They're not going to pass the virus to people who are taking measures to protect themselves.
The people in those pictures have made the choice to be there and take that risk. Anyone who was invited and didn't want to take that risk likely didn't show up or left.
We're past the point of everyone staying in. Now we're at the point of people deciding for themselves what level of risk they are willing to take.