Mainstream people are not travelling to Area 51 to be part of a flash mob due to an internet meme. Re-set your expectations of what normal people are doing, because it's a million miles off.
A once in a lifetime (incredible) celestial event == going to the gates of a military installation and, depending on who you ask, throwing a party or attempting a raid.
It's not for everyone, but it's within the boundaries of normality.
My other response has already pointed out your apparent lack of getting the joke, but it should be noted that if your primary hangup is the fact that people were partying at a military installation, you should probably know that specific base is one important to UFO mythos and thus public imagination. There is precedence for that at multiple locations:
Area 51, of course, is of higher security than these locations, but there's no crime to be outside of the restricted zone. Personally, I had no interest in the Storm Area 51 event but Groom Lake would make one hell of a hiking expedition. It'd be quite cool to take pictures at the gate, and try to spot black project aircraft along Route 375.
Mainstream people are not travelling to Area 51 to be part of a flash mob due to an internet meme. Re-set your expectations of what normal people are doing, because it's a million miles off.