My life experiences have led me to a rather negative perception of destiny. People pick out one of their kids, load them with 300x the advantages everyone else has, and then when they perform twice as well as someone with no resources, they retroactively perceive the decision to award the resources as justified by the result that the resources, rather than the person achieved. If you look at European sports for example, every competitor is given identical starting advantages, so if someone wins, you know they are better at the game. I'm a very logic driven person, so when I see a time magazine cover that says 17 year old Kylie Jenner is the worlds greatest self made billionaire entrepreneur, I think people are idiots, because they use the same language to describe a teenager that "said it was ok to use her name for marketing" as they did for Lee Iacocca, who singlehandedly resurrected Chrysler in the 80s. Who is a more visionary business person, an instagram model that figured out how to smile in front of a mirror, or Steve Jobs? Who was a more significant public speaker, Winston Churchill or Greta Thunberg? People can't seem to tell anymore. One recited a ubiquitous twitter post in an angry voice, and the other wrote 10k pages of geopolitical analysis and helped win the largest global war in history. But they both got the same magazine cover and title.
I'm sure it's not what you mean, but when you say destiny, I just hear nepotism. I'm definitely biased though. All the A+ students from my high school class (myself formerly included) are now employed as underlings of the D- students who came from family money. To be fair, it's not really like that on the coasts, when I moved out to California, It was sometimes the smarter people running the show. Here in the midwest, it's a hillbilly in a mansion telling a room full of coders with masters degrees to "make the computer do the business thing" Duck Dynasty, Duck Destiny. I'm not sure I'm really disagreeing with your point though, as I described, people constantly use the same words to talk about vastly different things. My life experience comes from living in an area where the guy who inherited the Indianapolis motor speedway owns the building that every research scientist slaves away in. He is an alcoholic day drinker with an IQ of about 90, some of the top engineering professors of our time work unpaid overtime in a building with his name sprawled across the top in 10 foot tall letters. I've been to their houses, some of them cost less than the alcoholic's weekend bar tab at Ruth's Chris.
My point is that it's always people that create this sense of destiny, and I've lost a great deal of faith in people's ability to identify a winner from a looser. We now have people at the top of the world who I do not honestly believe could graduate 8th grade if forced to retake the exams. We put every fighter pilot through intensive physical, intellectual, and psychological testing before allowing them to fly one armed plane, but if you came from the right family, you can order around the entire air force without taking a single competency test.
People often make the same point as you did, that one should focus on things within their control and ignore the situations of others, and that makes sense, up until the point you realize that your success or failure is basically decided by others, who are often driven by selfish and shallow motives. You only need to look at any meritocratic competition to see that many people feel as I do, that any situation where a lesser competitor can "pay to win" over a more formidable competitor is an ethically corrupt circumstance. Try giving a football team a 30 point lead at the beginning of the game and see if people are still singing ke sera sera. I can guarantee soccer fans would be rioting in the streets and burning down the stadiums. Yet we widely accept that type of situation in other areas. Just doesn't make as much sense as people say it does.
As far as the one hit wonders. I'm ok with all that, and like yourself I strive to create just one winning formula that can stand the test of time. It's in these stories that the last vestiges of the American dream still survives. You can be truly great for just a single moment in life, and make a fortune, leave a mark on the zeitgeist. They say every member of the Village People still lives comfortably to this day off of the residuals of YMCA. Def Leopard still performs "Hysteria" every night to a packed audience. Anyway, I hope you make it.