When I first started, I bought a 20g tank, and put smaller fish in it, since I wanted a community tank. I love how my fish all get along.
When I got a 10g for free, it came with a 5" angelfish. I donated him asap to my lfs. He not only outgrew his tank and was being stunted, I couldn't have anything in the tank with him. Now he has a bigger tank. And I hope someone buys him.
I agree that here in the US, new people don't want to buy a big tank with a couple big fish. We want our fish to live comfortably, and have a variety. Maybe when I get more advance in the hobby, I could breed and sell fish/plants.
I am also afraid of getting a bigger tank just in case it cracks, thats a lot of water on the ground.