I did it for fun, to learn, to gamble, and hopefully get lucky. God knows I've spent money in worse ways before.

Regarding the theory that other players would jump in the market and cause the opportunity to go away: you're right, but they'd really have to parametrize the same strategy in the same way as you. thousands of people use moving averages already, but all parametrized differently so they produce buy and sell signals at different times.

There's certainly no ideal parametrization that is alawys profitable, as most research shows (and I tend to believe)