How do I actually learn AI/ML deeply enough to build systems (not just follow tutorials)? [D]

I'm stuck in a loop where I consume AI/ML content but can’t move towards actually building real systems.

- I understand things at a surface level, but can’t apply them independently

- I don’t know how deep I need to go into math, models, or systems

- When I try to build something, I get lost between too many topics (ML, LLMs, agents, frameworks, etc.)

- I don’t know how to think like a developer/researcher instead of just a user

- How do you structure your learning to go from basics → real-world systems?

- What should I focus on vs ignore in the beginning?

- How do you practice “building thinking” instead of just watching tutorials?

- At what point did you feel confident building things on your own?

Would really appreciate advice from people who’ve gone through this phase.