Something has to validate transactions. If miners don't do it, who else will? Clients run by users won't, because they can't store the 50GB-and-ever-growing blo

Something has to validate transactions. If miners don't do it, who else will? Clients run by users won't, because they can't store the 50GB-and-ever-growing blockchain locally. They simply use the SPV protocol, which trusts that somebody else has validated the chain for them. As you can tell by the bitcoin.org alert, it was a serious issue that miners stopped validating transactions, because lots of wallets blindly trusted the longest chain, which was actually invalid. The majority hashrate can effectively determine the longest chain, and thus, most wallet implementations out there. Even if the wallets start doing limited validation, the Chinese miners could always exclude specific transactions they don't like.