Sicilian defense, Najdorf variation

Najdorf variation: Do you have any experience with this defense for black? Is it worth to learn the theory?

I have played it in the past.  If you are under 2200, the answer is no.

Like he knows so much LOL!!!

I don’t know about 2200 or anything, but, from my reading, I get the impression that the Najdorf is pretty much the standard example that people use to illustrate an opening that requires a lot of knowledge in order to be able to use it successfully.

It's a pretty good opening. Probably the best one against a 1. e4. But it requires a lot to learn. The essential theory in this opening variation is around 15-20 moves or more in forced theoretical lines. So the easy set-ups like in London system (around 7-8 moves) aren't going to work.

I like to play it when White gives me the chance, which isn't very often however. Lots of move 6 options for White so you need a lot of study time.

Indeed. I have 25 years of experience but I think its irrelevant for you to know that though. As non-important to have to ask if learning it is worth it. Every opening (black or white) has it's own merits. The Sicilian has a rich history, infamous. Like the Lakers, NY Yankees, Dallas Cowboys (I'm an Baltimore Raven Fan btw but yeah; Laker & Yankee fan for Life🤙🏼!) anyways... I disagree with Thriller if you're under 2200 (chess.com's rating I'm assuming) it's not worth learning. Just do it, my friend. I say, "hell yeah!" Its like Martial Arts, the earlier you learn it, practice, gain experience you can Master it. You are lucky to have soo many resources these days; I didn't. I just had RJF games, some GK games to go on. A couple editions of MCOs, GCOs, and a NCO, NIC mags, Chess Life stuff & many many notebooks filled with self annotated games. As it is, I dont know what it is you want to achieve; just play the Sicilian Najdorf~dont ever look for any validation from others. Best wishes ✌🏽