FIRST events cannot truly be equated with sporting events because at sporting events (especially college) there are designated sections. Of course I would expect to stand in the student section, and mostly sit in the alumni/family section at a Purdue football or basketball game. There are understood, defined areas for such behavior.
However, there are (usually) only two teams at sporting events, and the area each cheering section takes can be rather spread out to allow for standing/sitting sections. At FIRST competitions, there are dozens of teams represented, and the audience is segmented by team affiliation rather than by cheering style.
In my eyes, the people most affected were those unable to stand. We want our grandmas to be proud, but then we stand in front of them and block their view. We want to share our excitement with our siblings, but there’s no way a 10-year-old can see over a standing high schooler. We want to videotape the matches, but end up with footage of the back of people’s heads. My wife was enjoying her Arni’s personal pizza, but pizza’s not really a stand-and-eat-it type of food, and you can imagine the view from that perspective.
FIRST was created in part to destroy common perceptions - nerds can’t have fun, technology is boring, science and math have no real value, high schoolers are obnoxious and ill-mannered. Rudeness has no place in the world, and certainly not at a FIRST event.
Standing shows spirit, shows enthusiasm, shows support. But please be aware of your surroundings. The person whose view you are blocking may be a future alliance partner, an ailing grandparent, or a potential sponsor.