Why do laptops ask for BitLocker?

I'm curious, could you elaborate on why laptops often prompt users to enable BitLocker encryption? Is it purely for security purposes, or are there other factors at play? Additionally, what specific benefits does BitLocker offer that makes it a desirable feature for laptop users, especially those who handle sensitive data? And, if BitLocker is not enabled, what potential risks or vulnerabilities could users be exposing themselves to?