First off, congratulations on narrowing down your academic goals and career interests so early in high school! It’s a great accomplishment to be focused and know what you want.
As you’ve noted, many summer programs exist and the vast majority are ‘pay to play’ in that they require an application but most students are admitted. There are a few that are not only selective, but are academically rigorous programs that educate students on business and entrepreneurship in a very structured way, emulating future undergraduate business programs.
Without knowing your grades and overall profile, it’s difficult to say which ones would be most appropriate, but a couple to look into are MIT Launch, Berkeley’s B-BAY, Babson’s Introduction to the Entrepreneurial Experience, and arguably the most selective - Penn’s Leadership in the Business World.
Good luck in your research, and please don’t hesitate to contact Crimson should you need support in applying to these competitive programs! We have an excellent track record of students being accepted to the most selective and rigorous summer programs in addition to undergraduate colleges.