Riding for the US is a very very difficult goal to attain and difficult life once you get there. If you look at Olympic teams in the past most are made up of trainers kids who grew up showing, independently wealthy, etc. Riding in the Olympics isn't like gymnastics where it's mainly (all) kids who are trying to reach a goal before they age out. Most of the riders are people who have been riding and showing for decades. They grew up riding for big name trainers, ride multiple horses every day, often are home schooled so they can be on the road competing constantly, etc. It also takes an incredible amount of money. A maclay horse (and most of the big riders have done/won the maclay) is well into the 6 digits. Most people who are competing at the big shows (yes, even little pony kids) own multiple horses. For one of our clients to take one horse to a closer smaller rated show, they spend about $1500-2000 a week. I know people who's show bills at bigger fancier barns come out closer to $10,000 a week. It is a ridiculous amount of money that is involved. And it's not easy either.
Beezie's schedule is incredibly grueling. She spends her monday traveling to a new show and showing/schooling Tues-Sun from the crack of dawn to late at night. And sometimes throughout the week she leaves one show to fly to europe or asia somewhere and does a few classes, and flies back to finish off the original show. She takes a few weeks off in the winter for the holidays and that's almost the only time off she gets. Other then about 6 or 7 weeks in wellington in the winter and a few weeks in Spruce in the summer, it's a new show practically every week. A lot (if not most) of the international riders have this kind of schedule and still only 4 or 5 make the Olympic team. It's not always who's the best rider in the country either...it's who's horse is most competitive during the olympic trials. Some don't have a horse ready at the time and some riders have been incredibly competitive but their horse's start winding down when the trials begin and they don't make the team.
So... am I raining on your parade yet??? :) I'm not trying to! I'm just being realistic of what it looks like to get there. And honestly, there are a loooot of very respectable goals out there that don't include riding for the US. Champion at a rated show, qualifying for Devon, getting a ribbon at Devon, getting to Maclay regionals or even finals, maybe winning the Maclays, Young Riders.... Depending on where you are these are incredible goals to have and they shouldn't be discounted. And really, all goals to achieve to pave your way towards riding on a national team. I'd look into them, figure out what goals you can achieve and how to go about doing it, and go from there.