One thing someone once mentioned to me is that on a demo account when you sell/close your position, it is immediately closed/sold. However in a real trade you need to match to a counter party who buys the instrument, so it may not be as easy to make profits on a real account than on a demo account.
That's somewhat true, but nowadays the brokers are also market makers. Meaning if there's nobody to take the opposite position to yours, then the broker will take it.
What is however a problem with demo account is there's no slippage. When trading on a live account, the larger the lot size the bigger the slippage...and this will either cost or make you money
The biggest difference between a demo and a live account is...
YOU!
A real account is much more psychologically taxing, much, much more. And the reason is simple: no longer are you trading with monopoly money, money you lose or gain result in real losses or gains.
How much are you willing to lose before you walk away?
How greedy are you;when do you take profit?
How do you react when you lose a great deal of money?
This is the reason why some write EA's/robots which we program with our algorithms and leave on a VPS in Europe somwhere to trade on its own - thereby taking the emotions out of trading.
Why don't you run it on a server in SA you ask. Two reasons:
1) blazingly fast lines with very low latency to the Forex data centres
2) no loadshedding
disclaimer: this is not in any way, shape or form intended to be financial advice!!!