With my million dollar startup, it was years of research and stupidly hard work, and I had a tech and marketing background to build off of... and I had the luck of meeting the assistant to an Internet marketing "guru" in a bar and giving them a ride home. That assistant got the marketer to promote my product, which got others to promote. Without that bit of luck, it wouldn't have been nearly as successful. In truth, I probably would have gone bankrupt.
Another example... the year that YC startup school accidentally let everyone in, they had a speaker who was talking about what market fit looks like. They failed over and over again, building stuff nobody cared about. They had wasted nearly $500k of investment and were down to the last few dollars, and one of the founders had an idea. The guy speaking implemented it just to prove his cofounder wrong! That idea went viral and they grew into a unicorn.
In my opinion the talk wasn't about market fit. It was a cautionary tale about how lucky you need to get. Last I checked, I read that 82% of venture funded startups fail, even with all that money, talent, and connections. We rarely hear about them. We hear about the success stories, which expound upon the hard work and great idea and seem to overlook how much luck was a factor - and it always is a giant factor.
Having said that, I do think success can be engineered for some startups, if you have the time, money, patience, and constitution to go through lots of small quick failures to find that market fit, and then build your product with the support of a community. And, I think luck can be engineered for some people, like by going to conferences, being nice and providing value... and by befriending the assistants of influential people.