I understand the last paragraph, my question is more: what makes strategies not scale. Should you go looking in very niche sectors, where the transaction volume limits the scalability? Or are there particular classes of market insights that by their nature only allow (relatively) small profits? Or are there areas where one can exploit particular technical skills? Or maybe focus on geographically small areas somehow, which by their nature limit the potential profit and thus might keep out big players?
I'm not a trader and the level of my questions probably shows that; still despite my (amateur) research for years, I haven't found evidence of people successfully deploying such strategies. And while particular strategies of big players are secret, there is a lot of information on the general principles; for small setups, nothing (afaik). So that leads me more and more to the conclusion that it's simply not viable.
Looking at it another way: a trader who got his experience in a big fund, and who goes solo (a documented scenario), do they go after such inherently small markets, or do they do the same they'd do at a big fund only with less money or with less sophistication? In other words, if they'd have more money, could they scale up or not?