Why does Coinbase ask for SSN?

I'm curious, why does Coinbase request for my Social Security Number (SSN) during the account creation process? As a user, I understand the importance of security measures to prevent fraud and identity theft, but I'm hesitant to share such sensitive information. Can you explain the reasons behind this requirement and assure me that my SSN will be securely stored and protected? Additionally, what are the consequences of not providing my SSN, and how does it impact my Coinbase experience?