Didn't Mark Beaumont make a TV series about his cycling around the world while he was cycling around the world? That suggests that a lot of the groundwork of his subsequent fame was done before a pedal was turned. Somehow, he had pitched the idea, got the support and the commitment of other people to make a TV show, write a book, do lecturers etc and then all those people, having invested in the idea (and in Mark Beaumont) then had an interest in making Mark Beaumont pay off. They only cash in if he's famous so they all started working to make him famous. You make someone famous by making their achievements spectacular, dramatic etc By getting them booked on talk shows. So, although I suspect Arellcat is joking with the Neanderthal "Me big hero" thing, actually it's a clever strategy. You don't expend all the effort without there being lots of people committed to making it financially worthwhile.
I'm afraid I've never heard of Juliana. Has she made a TV show? Maybe it's not that she's less of a self-publicist but a less successful self-publicist. Maybe she felt it was more important to go quickly and get the Guinness record instead of doing something that was good to watch on TV or made a good book. It says on her website that "[t]he majority of her journey was unsupported. Without sponsorship or financial backing of any kind, she completed her attempt with the online donations of over 100 individual friends and supporters."
That makes her achievement heroic but it also means that when she's finished there's no product - nothing to sell and no group of people with a personal and financial interest in making her famous.