Demo trading is a must always, but I would say that if one is truly serious about becoming a trader live account training is also a must. Even if it's just a cent account, one has to learn to deal with the pressure of trading with real money.
Totally agree. Too much demo trading gives a false sense of confidence and security, when you put your own money down (even just a few bucks) you enter into reality and leave the perception behind. Demo is there to learn the platform, learn to code and test EA's, test strategies, get a feel for indicators, get a feel for market reaction, sentiment, events, news and charts... it's not there to teach you success and failure in trading because it doesn't affect you either way.
I compare it to driving a vehicle on a dirt / farm road (demo) vs. driving in traffic on tarmac (real)... you learn about driving in both circumstances, but you don't know stress till you hit traffic for the first time.
For every loss there should be at least an equal and opposite profit.