Anyone else lurk and feel like they understand nothing?

When I arrived here yes. Now I understand most things, join conversations and even get upvoted sometimes.

It'll happen to you too if you stay around and continue engaging in discussions. Don't be shy.

tawr

I feel like HN is one of the places where everyone can contribute, the topics are very diverse and sometimes random links that have nothing to do with technology are posted and have long discussions attached to them.

Sometimes topics you will be very familiar will be posted and you’ll notice that just because people comment doesn’t mean they know what they are talking about.

"Programming on and off" sounds like you haven't approached the field in a structured way. You can learn and accomplish a great deal that way, but it also means you have some gaps. Ever implemented a linked list? Compared sorting algorithm efficiency? Doing a course in computer science will probably give you a better grounding.

Also, people have niches. I'm guessing you're knowledgeable in your particular niche, and so is everyone else in theirs. HN is a broad church and you can find biologists and people who write optimising compilers, and either are going to look at the other's field with some bafflement.

Also, remember how it goes with learning things:

* Beginner: I have so much to learn ...

* Intermediate: I know everything!

* Expert: I have so much to learn ...

You might know more than you think you know.