If I were to compete in the Olympics myself (hahahahaha), I would definitely attend the opening ceremony. It seems like such a high energy event, and I wouldn't want to pass up my chance to wave a tiny flag along with thousands of other people who achieved their dreams. But, I am not an Olympic athlete, and so I don't have the self control that Olympic athletes have. For instance, the U.S. gymnastics team did not attend the Olympics opening ceremony, probably because they are there to compete, not to ooh and ahh over the outfits other countries decide to wear to the Parade of Nations.
As for why the 2016 Fierce Five didn't attend, none of the gymnasts explained the decision on their social media accounts or wrote anything about not attending. The NBC broadcast of the opening ceremony did note that Simone Biles was watching it from her bed.
One explanation may be that they just needed their rest. According to USA Today, the team decided to "save their legs" (i.e. not walk around a stadium) for their qualification round on Sunday. TeamUSA.org reports that the women had the entire day off on Friday, but trained on Thursday and have two training sessions on Saturday. On Sunday, the women will compete for the first time in a round of qualifications. Hey, nothing wrong with continuing with your day off to get some rest in before training. After all, the opening ceremony runs pretty late.
But even though Biles, Aly Raisman, Madison Kocian, Gabby Douglas, and Laurie Hernandez were not in attendance, U.S. gymnastics was represented in the Parade of Nations:
Way to go, guys! We're rooting for you, too!