Applications for facebook mod

I have been living with my boyfriend for about 7 months. Two weeks ago he sat me down and presented a powerpoint presentation with his business idea. I knew he'd been working on an idea, but he didn't want to tell me about it until it was finished. Based on his enthusiasm and his prior seemingly intelligent nature, I thought maybe it'd be a pretty cool idea.

Instead he presented to me an idea about "soup tubes". The idea, if you can call it that, is to construct a series of tubes throughout our city that leads to centralized soup kitchens. For a monthly subscription, a customer can "subscribe to a tube of soup", and a tube extension would be built off the nearest mainline tube and directly into the customer apartment or home. Based on subscription level, that would determine the quantity of soup a customer could pour and how many types of soup. The "tubes" are basically the size of pipes, like you might see under a sink, but he insisted that "it MUST be called soup tube, not soup pipe, tube just zings better."

I couldn't believe what I was hearing. At first I asked if he was crank yanking me or something, but he was completely sincere. Obviously, the idea is completely insane. The notion that the city would authorize somebody to construct a series of tubes everywhere that carry soup into homes is of course ludicrous. And even if such an initiative were approved, the costs for such an operation would be ridiculous. You would have to charge outrageous prices for customers to install and "subscribe" to a soup tube, and who would pay for such a service when canned soup costs like a dollar or two? Or you can buy soup from a restaurant for a few dollars? I explained these things as politely as I could but he dismissed them and all said that "tube based soup delivery is the wave of the future."

He then asked me how much I wanted to invest, and I told him nothing, and he looked absolutely heartbroken. Since then, almost every day he has asked again for me to invest, and keeps trying to sell me on the idea. He is also doing the same thing to a lot of his friends.

It is starting to drive me up the wall. First, I am at a loss as to how he can believe such a stupid idea is worthwhile, second it is really god darned annoying to be asked on a daily basis to invest in a system of soup tubes, and third I am also concerned for his sanity. Other than his apparent obsession with this though he has shown no other signs.

I would like some advice as to how I can reason with him, or whether I should even continue this relationship.

TL:DR - My boyfriend wants me to invest in a business venture wherein tubes would deliver soup.