The problem with HFT algorithms in the eyes of most hackers is they are almost entirely a zero sum game. Assuming minimal volatility and free trades the absolutely dumbest algorithm* will make money.
*Buy at X sell at X + 1cent with a simple ratchet of buy orders from 1 cent up to market price + a small number of shares to be sold if the market price increases.
PS: Random walk that averages +/- one cent 10 times a second = 5 cent's profit a second assuming ~2,000 trading hours a year = 360k profit. Cost to make that for a stock worth ~20$ = ~30,000$ of capital + whatever it takes to get on the HFT floor.
*Buy at X sell at X + 1cent with a simple ratchet of buy orders from 1 cent up to market price + a small number of shares to be sold if the market price increases.
PS: Random walk that averages +/- one cent 10 times a second = 5 cent's profit a second assuming ~2,000 trading hours a year = 360k profit. Cost to make that for a stock worth ~20$ = ~30,000$ of capital + whatever it takes to get on the HFT floor.