Yes, it is entirely possible to take FIRST and any other organization too seriously. FIRST is hard fun, it's addicting, you get that rush when something you design or build works for the first time. It's entirely possible to become too involved in FIRST though.
I almost did it last semester - I was heading up a Lego League tournament at Purdue and I was attempting to mentor team 1646 twice a week on top of 19 credit hours. I was stretched too thin and I knew it. You have to make accommodations in your schedule and life for FIRST, it's a big commitment. Next semester, since I've had three particularly heavy semesters, I'm going to take a lighter one - only 12 credit hours. This will give me enough time to mentor 1646 full time during build season, travel with them and Purdue FIRST, and do a project that I've wanted to do now for a long time with FIRST but have never had the time to do it. Keep your eyes peeled for something cool
Just don't bite off more than you can chew and your experience will be much more enjoyable and rewarding.