To be fair, Phelps has 23 Olympic gold medals. Some victories were closer than others but he really did have an era of true dominance.
And even that's got a certain element of opportunity in terms of the era you were born in. Tons of good athletes could have revolutionised their fields had they been born a few decades/centuries earlier. See British tennis pros, with the likes of Henman and Murray having had the potential to win a lot more grand slams in an era with worse rivals.
Still, other fields are a lot more opportunity and luck based. A lot of successful businesspeople got there by being well connected or simply having the right idea at the right time. Someone who had the foresight/luck to get into the vaping industry or bitcoin or whatever at the right time could become a millionaire/billionaire without any real talent. There are many YouTubers who can barely edit a video that got hundreds of thousands or milllions of subscribers via luck and timing. There are programmers who don't know what a switch statement here is how classes/OOP works who make thousands a month from game development on Patreon.
In many cases, talent and hard work sadly matters less than finding the right audience to appeal to, being good at marketing/sales and being able to network well/have good connections.
Seizing opportunities is a talent I’d say.
You’re falling for the fallacy that technical brilliance/execution is what matters. It doesn’t. It just needs to be good enough.
But at the same time, there are definitely success stories who just kinda stumbled into it too. Hell, I'd count myself in that camp too, at least at a certain level based on past experiences. I look at some of my past sites, and genuinely wonder how some of them took off. I was terrible at design, mediocre at best at coding, had little idea about marketing and had no network to speak of... and was beating out people who by all means should have done much better.
Even now, I've had people I admire complain that their years of effort on YouTube haven't paid off, while I somehow got three times the subscribers without knowing how to properly edit a video.
I know tons of people who stumbled to undeserving success, and tons of others who should have done well but didn't.
I don't know much about swimming but in bicycle races and skiing close results seem to be very common. Now if it really is "down to chaotic systems and butterfly wings" I wonder why we don't see much more variance amongst the winners?
But crucially, at the peak of the game, both talent and hard work are just the cost of entry. The rest is luck and opportunity.
For example: Phelps won the Olympics by a knuckle. That’s a difference so subtle it’s down to chaotic systems and butterfly wings for that particular race. Overall everyone at that level is hugely talented and incredibly hardworking