Here is how bitcoin is linked to information security.
First, bitcoin is an alternative payment system, which was created in order to resolve security problems of online payments, and theoretically can replace plastic cards everywhere, not just online. I hope everyone knows about security problems of payment card industry. If by any chance you don’t, read Hacking Point of Sale.
Second, bitcoin and its own security based on cryptography, which is one of the most important subjects of information security. If you want to know more about bitcoin cryptography - read Bitcoin for Nonmathematicians.
And finally, bitcoin is currently one of the main methods of payment on darknet marketplaces where bad guys sell results of bad information security: our stolen credit cards, medical records, bank accounts, etc. If you want to know more about darknet and data breaches… Well, perhaps I should start writing a book about it.