Different trading strategies will make money in different ways. Trading ahead and ticker-tape trading will redirect some of the profits that that an index fund would have made to the HFT trader. On the other hand, market making is in effect providing a service to everyone who wants to trade in the market, and they pay for it (partly through the spread between buy and ask prices -- this is like a fee for being able to buy/sell now rather than later, and partly through explicit ECN fees charged by the exchange).
Different trading strategies will make money in different ways. Trading ahead and ticker-tape trading will redirect some of the profits that that an index fund would have made to the HFT trader. On the other hand, market making is in effect providing a service to everyone who wants to trade in the market, and they pay for it (partly through the spread between buy and ask prices -- this is like a fee for being able to buy/sell now rather than later, and partly through explicit ECN fees charged by the exchange).