That's actually a really interesting analogy. I'm sure it's incomplete, but it instructs analysis.
Ownership of the beach is clearly valuable, even if it's unclear exactly how you will extract that value. And beach popularity can be subject to trends and other outside factors.
It's also easy to ruin a beach, and therefore its value by too aggressively trying to get the value out of it. For instance, I'd rather keep the beach free of ads and aggressive tourist sales people to make my money on hotels, condos, and restaurants near to the beach.
I'd say the biggest problem with the analogy is that only part of a beach's value is derived from the other beachgoers - there is some intrinsic value to the combination of sand, sun, and waves. For snapchat, if there are no other users, there is no value at all.