Because the bot follows the bid/ask price with all liquidity deployed at the price “front”. You have to have a very deep market the spread to have that much liquidity at the front normally. For example on ccedk the bot may have these walls:
price vol
123 50 sell
121 50 buy
That is a total of 100BTC
On btc-e it typically would be
price vol
130 1010 sell
125 460 sell
123 90 sell
122 30 sell
121 20 buy
120 50 buy
118 500 buy
115 1060
110 20
which has 3220 BTC on the exchange.
The nubot follows ask/bid price movement of btc-e, backed by more liquidity at the “front”, using 100BTC at ccedk. Traders at ccedk experience the price action of btc-e, backed by a lot of liquidity where it matters.
Of course this is not without problems. When there are a lot of big traders, as soon as the bot experiences big price movement with a lot of volume on one-side (buy or sell), it could run out liquidity and have risk of loss. Nubots running this way effectively are trading with leveraged-liquidity.
