[nexxer]

It's down to supply and demand. You get a license from local govenrment, buy some nice furniture, hire some young people, and set up shop offering a nice looking product of beach access with food, drinks, service at your umbrella, for 75 euro. More if you want front row beach access. You do leave the required free space for the public to put down their own umbrella (or not!). If you're the only shop on that particular beach, and it's a nice beach, people will come, and to enough of them your product will look "sexier" than the public beach area. By paying for it, they solve a need of theirs (beach fun) and can also brag about paying for it on social media.