I think it's an ending that gains a lot of extra resonance when considered in the context of the films around it - it takes the utterly depressing, but also in some senses saintly, image of the sacrifice of Ripley from the end of Alien³, and ironises it by turning it into a privileged, slightly bored with his life guy just having a lark, even if he doesn't exactly realise it until the slightly ambivalent ending. People used as chess pieces in some wider plan is taken up in Seven too.

It takes the idea of horrible, jolting events that should make you question your life, or should at least be cathartic in some ways, and then turns them into a theme park ride where the fear, or revelations about inner character becomes kind of undermined by its fakeness - or at least doesn't give the same longlasting impact that the events being 'real' would have. It's also about the transformation of the environment into a virtual space (a city as a literal playground for the rich), and the way that 'other people' don't really become important or significant until they have an impact on you personally, or until a paranoid state is induced. It condemns those people rich and bored enough to be able to get into this bizarre situation (as Panic Room implicitly does), but also exposes the unreality of privilege in fascinating ways.

Plus a lot of ideas from this film - of the kind of egotistical finale revealing that you truly are the most special person in the world, and for whom all of these people have been working in the service of; and of the commercialisation of lifestyle - of course gets tackled again in an interesting manner in the (working/under class) Fight Club.