Data Science might be useful if you want to work in Security Information Management or in malware analysis: big companies try to identify "weird behavior" in their networks, based on "normal behavior" records.
"Where can I learn cyber security stuff?"
Well, that depends on the stuff you are interested in...
You should focus at first on learning "system administration" and at least a programming language like Python or Ruby. Network protocols would also be a bonus.
Then, if you want to learn "offensive techniques" or "penetration testing", I suggest that you try websites like RootMe https://www.root-me.org/?lang=en or Cryptopals cryptopals.com.
Once you'll have resolved by yourself some of these challenges, you'll be able to try the "industrialized approach" of penetration testing. For this, this book is quite cool: https://www.nostarch.com/pentesting.
If you're more interested in "defensive techniques", you have tons of resources online.
For instance:
Secure Coding Best Practices: - https://www.owasp.org/index.php/OWASP_Secure_Coding_Practice... - https://security.berkeley.edu/secure-coding-practice-guideli...
=> These documents will help you to understand what are the main risks in your apps
For "general" cybersecurity: - ISO27001 standard - The NIST Cybersecurity Framework https://www.nist.gov/cybersecurity-framework - PCI/DSS - https://www.us-cert.gov/
=> These documents will help you to understand what are the main risks in an organization based on their assets.