I think Marx's position would probably be that personal success and exploitation in capitalism are inseparable from each other so the position argued here is fallacious. "His own efforts" presumably include adapting to markets that facilitate the transfer of the value of labor from the laborers to business owners. It's also sort of baked into capitalism the understanding that it is a competition, whose losers are not necessarily the product of laziness or weakness, but merely circumstance, so that sort of language is loaded; the subtext is that any indignity towards obviously unfair practices are just an inability to utilize them and not a moral concern. If you can't beat em, join em, etc.

But we see firsthand everywhere how hard working people don't get what they deserve. So it's not merely hard work that is required; it's cheating. Corrupt work. The better you are at cheating others out of their money the more celebrated you are, the more successful. Our titans of industry these days scarcely create; they largely provide maintenance services for existing transfers of goods or data and profit by eliminating overhead, which means people losing jobs.