Developing trading systems that are profitable is very hard.
Barriers to entry into trading are low, rewards for being right are high, the markets are very nearly efficient.
The basis of any trading system is to identify some inefficiency in the issue being traded -- identify some pattern that precedes a profitable trading opportunity. Making profitable trades removes a portion of the inefficiency making it more difficult to be profitable in the future.
Your competition is well educated, well trained, well paid, well equipped.
I agree with Geoff Colvin in "Talent is Overrated" and Malcolm Gladwell in "Outliers" that it takes on the order of 10,000 hours of high quality practice to become expert at anything. If anything, that is an underestimate for trading.
Thanks for listening,