Demo trading is like trying the platform itself, familiarizing about it though you can do the actual trading but there’s no risk on that and your emotion might not be present by that time but still using a demo trading at first is a big help.
I don't think demo trading has actually helped anybody learn to trade.
A couple of years back I tried forex trading with a demo account and it felt like I was learning because I was making profits, but when I started trading live, I lost all my money. I think that's part of the reason that discouraged me from foreign exchange.
What I find most annoying about demo trading is how easy it is to trade and make a profit. All this is to make sure you trade on that platform.
Normal to experience that situation since not all the time that what trades you do using those demo accounts will also happen when you are at real time trading using your own money. Remember that market is unpredictable so maybe that's the reason why you lose your money since you didn't expect some situation and you got caught up with it. But for me demo accounts are so useful because for this we can warm up or try anything that we can learn from before we use our money to trade since its really waste of money if we don't use this and we want to try some strategy so demo is there to save us up to know more about on trading.