Depends on what kind of time you're talking about and for how many years.
Not every gym demands military boot camp effort from their whole team. Lots of girls compete for AAU (around here, that's usually a lighter program with easier scoring) or for gyms that just don't happen to think that kids in the primary grades need to spend every single night after school at practice. And these gyms can be pretty competative, too. They might not win team title after team title, but they can produce some good athletes. So, if you don't want to commit to the "screwed-up childhood," shop carefully for your gym. Honestly, gym should not take over your life at level 4 or 5.
Another thing to consider is how many years you'll spend. I can't find newer stats on the USAG website, but in March 2007, there were over 20,000 athletes registered at level 4. There were less than 1/2 that amount registered at level 6. This doesn't mean kids don't make it, but that they move on. Other interests, an injury, a big growth spurt, puberty, a change in the family financial situation, or any number of other reasons might be the cause. So, if you put in the time, you may only have the "screwed-up childhood" for a couple of years. And there's nothing wrong with that. Had fun. Ready to try something else. Great.
From my own experience, we've been living the life of a competative gym family for 6 years now. My oldest "retired" after regionals last April. She was a month shy of her 15th birthday. My youngest, 12, is now training level 8 and 9 skills. Here's the kind of crazy I'd say is in store if you stayed in this over the long haul. Remember, though, you wouldn't hit all of this right away.
1. The kids go right from school to practice and don't get home until about 8:30 pm. We can eat together as a family only on Saturday nights.
2. Other activities have been squeezed out. When they were level 4, 5, or even 6, we were able to get in a season of soccer or something. Now, the only other sport we can play is softball--that's because gym practice moves to days in the summer and softball is at night. We're just lucky that there's no conflict with confirmation. Other families at the upper levels have had to make difficult choices between training and church.
3. Your car will be full of food wrappers and crumbs from all the eating on the way to/from practice.
4. School friends complain that your dd can't ever do anything, especially anything on short notice, because she's always at the gym. I've heard lots of parents say their kids' best friends are at the gym. Not so for us.
5. Since we're not wealthy people, we replaced "vacation" with "travel to meets." I miss vacations.
6. If you have other children, it may be almost impossible to give their activities and interests the kind of time and attention that gymnastics gets.
7. Did I mention is costs a whole lot?
Obviously, I'm still in this rat-race, so I can't think it's all bad. I think you'll get a lot of rosy "go for it!" comments, and I just wanted to point out that if you do wind up to be one of the few who is still in it after compulsories, you will have given up things that some people feel are way more important than a mere sport. Good luck with your decision.