Trading without loss is possible to some point, and this requires large volume of capital investment. Here the focus should be over a specific asset. Only then it is possible to observe the market. A very minimal profit margin needs to be set for selling, and same is with buying. As the market is volatile we've got more chances of the trade getting executed in a short time period generating small profit.
I am not sure trading result depends on the capital. If you trade using big sums, the benefits can be great. However, the losses will be also sufficient if you make a serious mistake. Trading without losses is never possible.