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Bitcoin is not anonymous, if it would be the question by OP could not be answered. Its pseudonymous, like e-mail.
Why is bitcoin not anonymous? What personal information can they access?
You are asking the wrong question. What personal information can you get from the e-mail address "
shor3na@gmail.com"? None, but when you send a mail to it you know it will always end up with the same person. Thats what pseudonymous means. There is an alias which masks my personal information, yet you can still know you send information to the same person using the same alias. Bitcoin Addresses have the same property. A fully anonymous system has no aliases. Everything would look identical or like random noise without any way to distinguish one person (behind an alias) from the other.
Why is bitcoin not anonymous? What personal information can they access?
Bitcoin may be quite anonymous if you use mixers, exhanges etc
You are funny, using exchanges would very likely blow your pseudonym as well as you need to identify yourself to the exchange. A mixer can help to avoid connections between addresses, thus keeping your pseudonyms apart from eachother. It does not make you anonymous. It just helps you to maintain your privacy.
see also e.g. here ->
https://bitcoin.org/en/you-need-to-know#anonymousWhen I transfer funds from the bitcoin exchange sites to my bank account, my identity is revealed.
But what happens if I make all my purchases online without making a connection with my personal account?
In short, I wonder if the bitcoin protocol itself is anonymous? Is our IP address logged?