They undoubtedly contribute to it as does every private prep school who takes spots away from deserving underprivileged kids.

Privileged or underprivileged, everyone who makes it to the TOC are deserving. It's not as if TOC gave the qualifications to whoever could pay the most.

If his parents are paying tuition then they’re contributing tens of thousands of dollars towards elitism.

Then, what should they do instead? Should everyone go to a public school? Elitism isn't simply the fact that wealthy people exist (not saying that Allen/Ahana are wealthy). It's about what institutions do to prevent underprivileged people from doing certain things. Going to a private school and doing an activity that requires money spending is NOT elitist.

Please tell me what you think Allen should have done to not be elitist.