I recall from Economy 101: the economy is moved by incentives.. Incentives in a wanted area cause that area to prosper, taxation causes an unwanted area to slo

I recall from Economy 101: the economy is moved by incentives.. Incentives in a wanted area cause that area to prosper, taxation causes an unwanted area to slow down. If a sipmle photoshop-plugin-like application like Instagram is worth U$ 1 billion, then of course you are bound to see 250 clones/mashups/whatever by thursday next week, because U$ 1 with nine zeroes is one heck of an incentive. The question on my mind is: are these websites worth this? Is a photo sharing app like tens of others out there worth this much? imgur is worth how many billions if instagram is worth a billion?