I think MOST people understand that it's rude to hog (chairs, tables, bar stools) in a crowded place, whether it's a restaurant, resort pool, or bar. Listen, we all want to enjoy ourselves, but we ALL need to be mindful that there are other people who also want to enjoy the place. Chair hogs are the worst. If you seriously want a lounge chair at your disposal every second that you desire it, then rent a private home. Otherwise, EXPECT to share things like exercise machines and lounge chairs.
And be courteous.
What does that mean? Well, when the resort is extra crowded, and seating is at a premium, only take a lounge chair when you are actively using it. (Duh.) Consolidate where you can. For instance, if you have 2 kids who will be in the pool a lot, have them share a chair, or let them share yours. It won't kill you to snuggle with your kid. Consider hitting the beach instead of the pool. And, for the love of all that is holy, when you go to lunch or to your villa for an hour long conference call, take your stuff with you so that someone else can enjoy the flipping lounge chair. Yes, there's a risk that there won't be a chair available when we return, but "reserving" your chair is only exacerbating the problem for everyone.