That's population not wealth, trust me I am sure most US businesses (technology based ones) currently don't have a strong foot hold in China. Which by your calculations make up ~15% of the world markets. If we however look by wealth and assume our allies are alright with our methods (given it also helps them spy on their citizens it's a fair assumption) we aren't risking that much, considering the countries we aren't in are the only ones who would oppose this.
I'm not saying that it's good practice to do what the U.S. did and I am appalled. However, they will not lose 95% of the markets, at least not now. There is currently no country with the capacity to generate as many new ideas into businesses, and the U.S. is roughly 25% of the worlds entire economy. Hell, just California is the worlds 7th largest economy.
Further, you don't think the other large nations (by economy), such as Japan, China, India, Russia, the U.K. are not doing/going to do the same thing (I omitted Germany and France since they seem to not wire tap.. Not necessarily true).
Business wouldn't and wont be cut 95%, I am pretty sure most countries are grateful the U.S. is setting precedent and will request them to issue warrants on their citizens.