How exactly do we make money? (Can a lighthouse be profitable?)

The answer is, of course, yes! At least, as long as lighthouses are necessary. But how? Ships do not pay to pass them. Well, ships sail under a flag and do business with ports. This can be regulated. As well, those businesses who do shipping at a port can be made to pay a tariff in order to conduct business through such port, like a membership to the port, in varying degrees of permanence. All of this trade is dependent upon the lighthouses.

However, it is up to a lighthouse to justify its existence. At first it is justified by shipwrecks, as in, the need is paid for in blood. This is often the case. However, once a lighthouse is built, ships generally are not wrecking upon its shores. Then, it becomes incumbent upon the lighthouse keeper to keep watch over its waters and pay mind to those who traverse with its assistance. Surely not all vessels will be noticed, and a dishonest lighthouse keeper would be easy to spot after some time.

To calculate the return on investment we would first calculate the cost to build the lighthouse and then amortize that across the anticipated lifespan of the lighthouse. We might suggest to keep this within one human lifespan, so as to make the value calculable and not approach infinitesimal at infinities.

Is this conversation even relevant?

A good question, and a fair one. It seems reasonable to question the modern relevance of this as an example of anything.

Indeed, lighthouse do seem obsolete in today’s era, however this is a misconception. Lighthouses can serve a great many purposes far beyond simply passing a beacon of warning for seafaring vessels, though this need per se is no less today than ever.