Imagine I build and launch twitter2.com. I put a lot of hard work into it. It fails, of course. Was I unlucky?
Obviously there is (at least) a 3rd dynamic at work. It's hard to nail it down, but let's called it insight.
When I first saw twitter, soon after it was launched, I thought it was stupid. Actually, I still think that. But obviously they were onto something. Obviously the market for that kind of service is much larger than I would have imagined.
They worked hard, no doubt. They had luck, I suppose, that the idea first occurred to them, that they had the skills necessary to pursue it, that they were born into a rich society with the leeway available to pursue speculative opportunities, etc. You can go as far as you like with that kind of digging.
But without insight, that people would want such a thing, they'd have nothing. "Luck OR hard work" is meaningless. It removes any kind of decision-making from the equation. That decision, of what to work hard on, in which arena luck might have the opportunity to shine on you, is critical. Anyone can work hard. Anyone can experience a little bit of random luck. Insight is what ties it together, turns good into great, turns mere effort into rousing success.