Because they're valuable, 15-20m pounds of Fla's annual yield was being picked years ago, often by companies that payed $60 per 100 pounds, and not on their own farm land, but on public land, it seems, and there was trespassing on private land (even if the owners didn't care about the berries they didn't want people trespassing on their land). Picking the berries prevents new seedings which degrades the plant's presense. It is one of the foods of bears and tortoises there.
Ie profitable enough that people would just do it until there isn't any more, which we've seen with other species.