Your question seems to be is it all luck? NO it's not. There is a lot of luck involved with domaining, first off you can't just go and make your own way, you need the misfortune or negligence of others. By that I mean there are plenty of names that sit and don't sell for 15 years, many brandables have been like this and then someone lets the name drop and someone else picks it up and sells it passively, just putting it on Sedo and Afternic (nothing that requires skill or high intellect) in three months. That is pure luck, now you will not be able to make a living doing that, outliers happen and other bits of luck happen as well.
Look the whole secondary market is based on luck, GoDaddy and all the other registrars that sell their customer's expired assets and pocket the cash got lucky. ICANN could have easily implemented rules that said all names expire after 30 days and are released back into the wild. A registrar cannot profit off of expired domains, they didn't and that was very lucky for companies like GoDaddy.
Understanding linguistics, marketing, trends, the temperature of the culture and knowing how to sell are all real skills you need to adapt to make a living or a hobby where the juice is worth the squeeze.
But for anyone telling you that luck played no part in their success in this business is either lying or in denial.