If you kill the cow that are giving you milk, you will lose milk production. So why would you want to kill the cow?
The people saying this, do not know how the consensus work and how decentralize Bitcoin is. If China stop all mining and nodes, the network will still exist in many other countries. ^smile^
Hmm,
Maybe you should study decentralization ,
Fact : China Mining Pools Combined are more than 51%
Fact : China like all Governments can exert control over any Entity inside their borders by Regulations or by Force.
Fact : 51 % attack is a valid concern and sticking your heads in the ground about it , is foolish.
Reference: In his Bitcoin paper, Satoshi identified several issues, with the 51% attack being the greatest.
http://www.btcpedia.com/bitcoin-51-attack/
Myth: China stop all mining and nodes, the network will still exist in many other countries.
Why on earth would they go thru all of the trouble to Completely Dominate it, merely to give it up.
They have an intent and purpose planned for their BTC Dominance , and it will be carried out on their timetable.
They could increase fees on all Foreign Countries while discounting in their country, they could hold your BTC for ransom or for Political Compliance of one of their Agendas.
You would comply to receive your BTC. Look at how they control their Yuan, their business, and their People , expect similar control of BTC when ever they deem fit.
Giving up Control of BTC would be Stupid, and the Chinese are many things, Stupid is not one of them.
Fact: China mining pools already blocked BTC XT from going to the 20MB blocks because their internet infrastructure would not yet support it.
https://cointelegraph.com/news/chinese-mining-pools-call-for-consensus-refuse-switch-to-bitcoin-xt
Fact: BTC is still having Transactions delay problems because the 20MB were refused.
http://www.ibtimes.com/bitcoins-big-problem-transaction-delays-renew-blockchain-debate-2330143
Observation: When Ghash.io passed the 51% everyone in the BTC Community was terrified.
https://www.extremetech.com/extreme/184427-one-bitcoin-group-now-controls-51-of-total-mining-power-threatening-entire-currencys-safety
But now that the Country of China has done it for over a year, no one is concerned.
Fact: Satoshi himself listed the 51% attack as the Greatest Danger to BTC, and now the Majority of the BTC community ignores his most important warning.
The Chinese Officials are smarter than all of you BTC Advocates, with your heads in the sand over this 51% attack security threat.
Warning: When you make another entity your Master, be prepared to be Punished at their discretion.
Good Luck , you are going to need it.