Don't worry about it. EVERYONE started from zero. And then MSFS came along and we all had to start again. I spent over 10 years using FSDS for modeling and I had to learn Blender when MSFS was released so I'm no expert in Blender yet.Considering I knew absolutely nothing (ZERO!) about 3D modelling or Scenery development this time last year (16/9/2021 was the date of my first package, let alone a 3D model), I'm more than happy with the progress I'm making!
One of the problems with general Blender tutorials is they are geared towards people who render images so massive models are not an issue for them. For game design there has to be a trade-off between model complexity and visual fidelity so you always need to keep one eye on the total triangles in your model.