> Then why people are not doing it? Take a look on the list once more:
I did. Notice in the November 2012 list that Intel doesn't make the top 5 at all. Yet Power and SPARC do, both considered RISC chips by most people I think (although Power is debatable).
x86 got to the top just because of economies of scale and because it is good enough, relatively cheap. Being able to buy things off-the-shelf does help. Having spent some time in an HPC group I can tell you that x86 is used because it's there, not because it has any real benefits. How long has it taken them to get a fused multiply-add instruction?