Back testing and its flaws.

I've seen it countless times, people wondering why the back test shows profitability but the second they go live with a real account it loses money. Well, the fundamental problem is a bot doesn't trade like a human.

Say you have a MA cross at 1.11111 to keep the example simple. Price was at 1.22222 but you come back and it's really closed the trade at 1.00000. Why? Because the bot is only figuring things out when the bar/candle closes. The price it executes can be vastly different than the price you would execute at, unless the bot submits the SL as an order and also knows not to immediately open another trade.

You would have seen the MA cross and closed out the trade immediately, the bot