>But if I sell you a hand drawn stick figure for $100, and you buy it with the mutual expectation that it will eventually be worth more because of the value of the brand/project, and the effort I put in to grow that value... isn't that a security, by definition?

This seems equivalent to buying a baseball card of a specific player with the expectation that the player will put in effort into the game and thus increase the value of the card. People buy cards of specific players on the assumption that they can buy in cheap and sell when the value of the player's brand increases.