When you take advantage of the possibility offered by many online brokers to practice trading in a demo account with "fake money" to get yourself acquainted with their platform, brokers usually state — either explicitly or not — that such conditions are very realistic. However, that is rarely the case.
We already wrote about how emotion influences your live trading, so we will not spend much time on this here, if not to direct you once again to our free psychology e-books section to learn more about it.
Even when you pass from trading 5 standard lots of "fake" money to just a single mini-lot of your own money, the emotion will simply be overwhelming unless you learn how to control and manage it by setting (and not changing along the way) predefined stop and limit orders to confine possible losses and save your profits.
Having a large amount of money at your disposal has a huge effect on your trading possibilities, even in terms of strategy and money management, which gives you the impression you can just "buy and hold" and consistently be profitable that way.
Unless you really know what you are doing, it is not like that in the real world. Do you really have the nerves to buy and hold, even when your losses are being leveraged 50, 100, even 1000 times? Unless you are taking a calculated risk, chances are you will get a margin call even before your trade has a chance to recover.
High equity also greatly reduces the risk of margin calls. Do not make the error of trying to simulate what you would do with your money by trading mini sizes, and then forgetting to set a stop-loss. Buy and hold — although extremely risky — is practically bound to work in the long term that way, but this does not mean that it will work with much smaller equity.
In other words, if you have an equity of $100,000 and trade just one single lot of 100,000 (a standard lot) with, say, 1:200 leverage, you can afford to lose many more pips than you could if you only had an equity of $2,000 under the same conditions. If you try to buy and hold, you will trigger a margin call sooner or later — do not forget that.
A few final tips to prepare yourself for the "big jump" from demo to live trading: