In response to the original post, I think it would come from a lack of relatability on the viewers end. Not all, but a chunk. I'm sure a good percentage of those viewers on say LZ or TJ's channels, are people interested in cars and videos about such, but not so much the work, effort, and behind the scene shit that goes into doing some of these builds and what-not, which are generally cut out or shortened in alot of those LZ or TJ vids (or at least from what I've seen. Could be mistaken). I think a good part of it would also be that, you keep things real, while some of those bigger channels are a little bit more rehearsed and planned out, whereas your videos are a bit more raw. Being that you keep shit real, it'll definitely be a harder climb to the top, but persistence is key, as cliche as it sounds, and I'm sure you'll get there if you keep your mind to it. Also gotta keep in mind that youtube comments generally consist of 12 year olds and keyboard warriors that'll do anything to get a rise out of anyone, with but a handful of genuine comments that can be trickier to find amongst the cancer that is, the youtube comment section.
You keep shit real, they keep shit a little more "trendy", for lack of a better word