Trading is simple...once you understand the complexities :)
Trading is a business...you are essentially competing with other business people, therefore your knowledge/business plan must be better than 95% of the other business people.
Consider that most people or 50% who start a business quit in around 12 months...another 25% quit in the next year and so on...in 5 years only 1 in 20 of those who began will still be in business, these people will do ok and make money though some will still fail. The numbers are the same/similar for trading.
You must have an exit plan and know what the business will cost you if it fails before you even begin, in trading this a stop loss. You must know when to sell your busines and not get emotionally attached/greedy...in trading this is a trailing stop etc.
That is essentially all you need to make money from the market, you just have to fine tune the above and look for investments that have a good probability of the share price rising.
I am in the black this financial year, I am a sophisticated investor and a previous stockbroker and have my own investment company, I have also lost the lot once before and learnt my lesson well, I have learnt how not to lose money first and then learnt how to make money secondly. I have seen how people/trade invest and know first hand the vast majority fail and I have seen how they fail.
Trading is not about knowing companies, it is about knowing the psychology of markets and those who make up the market.