AITAH for missing my sibling’s graduation?

Basically my brother will be graduating in June this year from college. He told everyone about it a few months ago. Unfortunately, I already booked non-refundable plane tickets and a hotel by then (totaling $2k) for a solo trip during the same time as his graduation 😩 . It’s a trip I’ve been planning and looking forward to for a while.

My parents and brother say I should forfeit what I already spent and opt to go to his graduation

However, I feel conflicted because it would be nice for me to go to his graduation but I also don’t want to miss my trip or lose out on the money I spent. It also doesn’t help that his graduation activities are a total of 3 days (right at the tail end of when my trip ends). I wish he told everyone the month he was graduating sooner rather than only a few months in advance.

AITAH if I don’t go to his graduation?