As Sandi said, Disney could open it to anyone, but so far they have chosen to restrict it to
DVC members. When BLT first opened, only members staying at BLT could go up there, but apparently the lounge didn’t get enough business that way. Over the years eligibility has gradually expanded - to DVC members staying on property, now to DVC members in general (I can’t remember when the DVC-Y requirement came in, probably when the blue card/DVC-Y distinction came into existence). And they’ve added the extra-cost events over the years. Everything they offer is designed to bring in enough revenue to justify continuing operations. I’m sure they hope that making it DVC-exclusive adds to the lure, but if at some point they determine it’s still not bringing in enough revenue, they’ll either open it to anyone or close it down and just use it for private events. That’s what happened to The Attic at BWV.