a good read for millionaire's play https://www.csoonline.com/article/3243293/security/whos-who-in-the-cybersecurity-market-the-inside-scoop-for-2018.html
Read it fully, if you want to increase your knowledge.
The cyber crime epidemic — which is expected to cost the world $6 trillionannually by 2021, up from $3 trillion in 2015 — is fueling the market for cyber defense solutions. Add in the growing compliance mandates, including GDPR and its May 2018 deadline, and the cybersecurity market figures will rise to dizzying heights over the next decade.