I think you need three things to make it in this industry, and without any of them, you're screwed. Talent is one, persistence is another, and frankly, luck is the third
I'd rank persistence first and foremost. It is possible to substitute diligent craft for talent, though talent helps like crazy. Diligent craft is pretty essential in its own right as well, with or without talent, but that probably falls under persistence. Luck is funny concept, though.
The thing about luck is that you have to be ready to be lucky. If I find an original copy of the Constitution behind a picture frame, and I don't recognize it for what it is, how lucky is that? I've certainly been lucky in my career, but it hasn't been random luck. I've worked very hard to put myself in the position catch a break, and to know what to do with that break when it came my way.
Luck, for a writer, has a substantial component of business knowledge, craft awareness, and rational expectation embedded in it. All this natter about writing process and networking and the business of the field is in a very real sense, preparation for being lucky.
Specific example: What if you get in an elevator with arcaedia one day at a con, and she asks you what you're working on? If you're prepared, you know who she is (an agent with a good client roster including that clever fellow jaylake). If you're prepared you have a high concept, one line pitch for your novel on the tip of your tongue, which you spent the two days before the con rehearsing in the bathroom mirror. If you're prepared you can answer a followup question or two.
Now, was it lucky to run into an agent in a quiet, receptive moment? Sure. But if you weren't ready for it, that luck meant nothing.
Sometimes people say "luck" and they mean "I found a $100 bill in the street." That's random chance, and it happens too. The luck of my career has been almost entirely the luck of preparation and quick thinking. In others words, luck I have some control and influence over. How lucky are you? Are you prepared to be lucky?