the big data make anonymity become more and more difficult.
What do you mean by "the big data"? Blockchain info?
I think he means the mass surveillance program which includes data from millions of web-trackers, social networks including facebook, email services, phone conversations, instant messengers, google searches and the list goes on. All of this data is collected and accessible by employees of the NSA and private contractors without a warrant, both private and public information. To be anonymous these days you need to take extreme precautions, because there is money to be made in stalingrad surveillance systems
Not even just the NSA. With Bitcoin anyone can do analysis fairly easily. Tools for data analysis are easier to use now more than ever and anyone who can code a little can take a bit data set and try to get some useful information.
yes, but in relation with anonymity you need an enormous dataset which at present is only accessible to large corporations, private contractors and organisations like the NSA.