Developer Seeks Free Alternatives to TryHackMe for Learning Pentesting

A user with 8+ years of experience as a full-stack developer and data scientist can no longer afford TryHackMe and is seeking alternative ways to continue learning pentesting and cybersecurity. They valued TryHackMe for its hands-on practice approach and want to learn to identify and fix vulnerabilities in their personal projects. The user is open to various alternatives including free/cheap lab websites, books, self-built VM labs, vulnerable machines, free CTFs, or any structured learning path, emphasizing they want to understand the why behind concepts rather than just following walkthroughs.