While I get what you're saying, "most people only go to Paris once" is a very odd analogy to use in this case. Paris may be a tourist destination, but it's not a tourism company. :)
In any case, I think the caveat to what you're saying is that the sustainability of a business proposition that many people only do once (or at least, do comparatively rarely) also has to take into account the cost. Very people take a Jeep tour of the Grand Canyon, but the Jeep tour company is almost certainly a very lean operation compared to 23andMe.
In any case, I think the caveat to what you're saying is that the sustainability of a business proposition that many people only do once (or at least, do comparatively rarely) also has to take into account the cost. Very people take a Jeep tour of the Grand Canyon, but the Jeep tour company is almost certainly a very lean operation compared to 23andMe.