I've always thought that any sufficiently funded team of professionals could blow Bitcoin out of the water in a short period of time. I'm surprised it hasn't happened yet to be honest. Probably still too niche.
Blow bitcoin out of the water with what?
With a budget of 150 million USD, a group determined to push a "FooCoin", with similar protocol but independent blockchain, could hire the top 3-4 mining companies and switch the majority of the bitcoin hashrate to mining FooCoin, for three months at least.
Combine with some flashy bells and whistles, a TV marketing campaign, support by Apple and Facebook, perhaps some biased government regulation, and perhaps in that time the FooCoin will get enough newbie demand to stand on its own -- namely, with such a combination of market price, difficulty, and block reward that it would attract more hashrate than Bitcoin, even without the external subsidy.
That would not kill Bitcoin outright, but it would take away its "network advantage".
Could such a plan work?