Sure, even small hedge funds and propriety trading firms are generally working with millions of dollars.
I agree there must be some niches are that are amenable to exploitation by small independent traders (perhaps anything to do with nanocap stocks).
I have not had success finding niches where I thought I would be successful, but I could very well be insufficiently clever.
But trading highly liquid equities on a multi-day timescale (the strategy proposed here) is certainly not prohibitively hostile territory for large, sophisticated buy side operations.