I think that overall, what you're saying is true, but I think you put a bit too much emphasis on "luck" and this bolded text in particular.
I've attended, since its inaugural year, what is now the largest annual video game devs conference/mini-E3 in Western Canada. I've met one other composer who can be bothered to show up to whatever kinds of events are going on. I've met a composer who showed up blasting bad music sequenced with Guitar Pro and when (surprise) no one hired him, he never showed his face again. The story rings true in the indie-film scene as well.
The most successful rock band where I'm from, is Nickelback. Every other rock band around here can't be arsed to learn to play to a click track, won't learn even BASIC music theory and are just terrible in general. For all the hate they get, Nickelback is the best and most competent band we've ever produced. Every group of overweight guys and their attempts at "metal" shit on NB though and no word of a lie, the average elementary school is producing more competent musicians than these haters. Yet, they can't understand why they rarely get gigs and they're always unpaid; it's the Dunning-Kruger effect in high gear.
I've made more money than any EDM producer, rock band, etc. in my area that I know personally (and I'm certainly no millionaire) 6 years ago, when I wasn't even half the musician I can be now, off scoring indie games and stuff simply because I was willing to try and learn and improve best I can. I'm willing to get out there and meet people, I'm always trying to learn how to compose better pieces, learn more theory, etc.
Yeah, luck is involved, but that "luck" is more the result of working hard and placing yourself in situations and relationships that can open doors for you. It's like the luck involved in any other field you try to break into: You can't just GIVE yourself the job, but you can do can your best to (hopefully) make yourself a much more attractive hire than your peers and hope for the best — it's all you can really do, but if you don't even give it an honest effort, you'll never succeed.
The truth is: If there was a recipe for success, most people couldn't be bothered to put in the requisite work necessary to do those tasks.