166667 avalon chips to absolutley dominate bitcoin network

[vnezapno]

I know that  this won't happen 'couse doing this for an asic chips manufacturer is like blowing up the goldmine but think a bit.
If 1 avalon chip is 300 mhash and total network hashrate is 100000ghash for now they need just 170k chips running to absolutely dominate bitcoin network.
Considering 1 chip 0.085btc (and of course net cost is MUCH less) one asic manufacturer would need just ~1 million dollars and asic chip factory to do whatever they want with bitcoin.
I know that in practice that won't gonna happen(nobody wants to blow the goldmine right ?) but don't you think that even hypothetical opportunity of such an easy scam should lead us to conclusion that sha256 is not good enough to provide appropriate network decentralization.

[macmn]

That is kind of scary, and part of the reason why I have migrated to alts such as LTC