"I'm only interested in FAANG money and retiring early"
You literally have no intrinsic motivation to solve hard problems other than getting paid more.
Focus on learning and acquiring skills and solving problems, not trying to get "FAANG money".
Leetcode has nothing to do with FAANG money, sure, knowing algorithms and how to optimize code helps, and that's the only commonality between FAANG interviews and leetcode, but those things can be learned outside of leetcode. Simply taking a few CS algorithms courses will make it apparent that 90% of leetcode problems are found in some variations inside your undergrad CS algorithms course.
Sounds like you need to reset your values and re-align your priorities.
You got fired for performance reasons as you mentioned. "Had" all these resources and time spent on trying to improve yourself, but you just want a "FAANG salary". This is not the way. Either you love CS as a field and you love solving hard problems, or it's not for you.