If you apply for something that's highly selective, it's tempting to think that you'd be foolish to turn it down if you're fortunate enough to be accepted / chosen. But, it's important to reflect on whether it's actually a good fit for you. Often scarcity and prestige are used as tools to convince people to do things that they'd otherwise find repulsive.
Remember that what makes you happy and what makes others happy aren't necessarily the same thing. So, while many people might say "yes" without reservation, it's fine if you can't do that. Having the courage to say "no" will save you from the difficult process of trying to undo your decision if you don't like it. Trust your instincts and try to see things for what they are, because often they're not all that they're chalked up to be.