If I make a winning system, yes, I抦 going to sell it?like all others

The reason is simple. Why not make even more from something that already brings me a profit. Plus there is another aspect. Markets have cycles and not a single winning system is winning all the time. So why not make the most of something that has proven to work well and we all know that it抯 not going to be forever.
But the real question is different. How would you convince me it抯 a winning system? By the backtest you have runned? There are already thousands of such winning systems and except for beginners who think that it抯 the holy grail, not a single serious trader is willing to buy such a system.
Let me illustrate with an example.
You think that a winning system is hard to make, then create a losing system. I will buy a losing system if you convince me that, at the end of each specified period, the system will lose money. Give me a guarantee that the trading system will lose money and take my money. Once I have a system that is guaranteed to lose money, I'll just flip the trade direction and I have a winning system.