Neither Japan nor Europe can point to a similar set of companies. Americans are taught to look for the big technological breakthroughs. Our elite engineering schools don't give much credit for one percent improvements. Starting a new business is a thing to do. Getting re-employed if one fails, and many will, is easy.
Venture capital is plentiful.
Many activities were closed and moved to cheaper off-shore locations. In the process, Americans globalized their production much faster than either Europe or Japan. None of this means that the United States is permanently up and Japan and Europe are permanently down, but at the moment the United States certainly has momentum on its side.