No [****] owning a boat is expensive! But you can manage many of the costs if you really want a boat. You can get a mooring instead of a slip, you can do your own maintenance, if you live up North and your boat has to be drydocked for the winter you can store it at your house instead of a marina yard. If you don't love boating get the hell out.
You can't protect people from themselves. Anyone who doesn't understand owning a boat is not a practical decision has reached a stupid conclusion.
Anyone who buys a boat and doesn't research the annual costs to determine if they can afford them has made a stupid decision.
Anyone who can't get out on the boat enough to justify the expense that they can afford, is either whipped or doesn't really love boating.
You don't have to be stupid to make a stupid decision, but it sure helps.
As one renowned redneck would put it, "Here's your sign"