Couples who plan destination weddings typically expect a very small turnout, but if the host hotel is that expensive, they've gotta be expecting an even smaller one than usual. Unless you're close family or a VERY close friend, they're probably not expecting you to go.
I did use a friend's wedding as an excuse to see Hawaii (Kauai) a decade ago, and it was fucking amazing, but I was able to secure a great studio for like $150 a night. $750 is steep af.