why not heavily trade?

In 1963,Paul Samuelson was having lunch with one of his colleagues ,another economist,E.Cary Brown.Samuelson,in a playful mood,said at lunch,hey let's toss a coin,let's make a bet just for the fun of it,and if it comes up heads,I'll give you $200,but if it comes up tails,you give me $100.He said ,let's do it I'm ready.This kind of took E.Cary Brown by surprise.E.Cary Brown said,come on I don't want to do this, Samuelson was being annoying by doing this.Then Samuelson had another idea,he said,what if I offered to let's do this 100 times,We'll toss a coin 100 times and each time it comes up heads I give you $200 and each time it comes up tails you give me $100.This time ,E.Cary Brown said ,well,if we do it 100 times,I'll do it .of course ,they didn't actually do it .Samuelson then said he went back to his office and he wrote a paper(something called Prospect Theory) ,proving that E.Cary Brown was irrational.

Then what is your idea? was E.Cary Brown irrational? if you were E Brown,what is your choice ?I think the game of tossing a coin is absolutely as same as forex trade.Forecasting exchange rates has a success rate no better than that of forecasting the outcome of a coin toss, Alan Greenspan said. and fti said ,three very important ingredients for you live in any markets :One is " Market Structure ", the other is "YOU", then Capitalisation. Agreed!

I think i have understanded something ,and you ?

Obviously you would want to go for 200$ profit when you win and 100$ loss when you lose.
If I got a 50:50 chance to gain 200$ for 100$ risk, then that is an awesome positive expectancy system, which will be able to give you vast amounts of money in the long-term. But I think forecasting price direction is actually not that difficult. Earthquake in japan = higher yen due to repatriation of money (You would have known that from the kobe earthquake a couple of years back). Then the national banks announced that they will not allow a high yen and intervene. A no brainer for shorting the yen.
NATO decides to attack lybia, which has large oil reserves. Good for oil and thus good for oil rich nations, a no brainer to go long cad and aud. When greece first announced that it has severe problems and might default, a no brainer to short the euro. Combine that with some technical analysis, then you got a system that is for sure having a very high win-rate higher than 50:50 chance and a good R:R as well.

This makes complete sense.

If you do not have a statistical edge, then you would do best to do an all or nothing single trial (i.e. one flip).

On the other hand, if you have a statistical edge, then you want multiple trials (flips) because you know that as the number of trials increases the more the outcomes will approximate the true probabilities of the event.

While streaks (or trends) are possible, the more times the coin is flipped, the more the results will resemble 50/50. Think about Vegas. The casinos in Vegas would rather a gambler make small bets for hours than one large bet as soon as they arrive and leave regardless of outcome. Because the house understands the theory of large numbers.

Ultimately, they were both being rational. The person with a negative expectancy is rational in wanting a one shot trial. The person with a positive expectancy is rational in wanting to allow his edge show up over time in multiple trials.

A higher reward to risk ratio as a stand alone method is not going to work.

The more you skew the risk to reward ratio in favor of reward the more your inversely affecting your probability of winning that trade. It would probably over time work out to be a 50/50 shot at being profitable. Count for the spread and your at negative expectancy.

Money management is a tool not a method.

I have great respect for Alan Greenspan.
In his younger years he toured as a musician and was part of Ayn Rand's
'inner circle' briefly.

Later, he earned a Ph.D. in Economics and eventually became chairman of
the Federal Reserve.

Just like many economists, Greenspan would probably make a terrible trader.
I'm certain Bruce Kovner and Bill Lipschtuz would argue against his often
quoted quip. They have been trading the currency markets for 25+ years.

yeah, I heard somewhere that most major economic predictions of greenspan have been completely wrong. He would have been a seriously bad speculator.

This analogy is flawed.

In Forex, the chances of you being either "correct" or "incorrect" are not 50/50. And setting a higher TP decreases your chances of success, whereas setting a higher SL increases your chances of success.

In this case, you are arbitrarily setting the $100 and $200 reward amounts. They are NOT the same as SLs or TPs, because they have no bearing on the fact that the chances of the coin toss resulting in either heads or tails is ALWAYS 50/50.