“Two Groups Account for $1 Billion in Cryptocurrency Hacks, New Report Says,” The Wall Street Journal, January 29, 2019. The suspected hackers are still active, and there are many others as well.
Willie Sutton, when asked why he robbed banks, reportedly said (but personally denied saying, but why believe him?), “Because that’s where the money is.”
Cryptocurrencies, like bitcoin, are Information, in a sense, with a monetary value. Protection of such currency in place, in a digital world, is Governance (you have a fiduciary duty to protect the assets entrusted to your care), and Compliance (with law and with company policy). So, security is a bit Governance and a bit Compliance.