How does it shape the market structure on a chart and form patterns with such low volume by speculators?
Patterns form from random generated data and from fully automated market participants. For them not to occur over longer time the efforts need to be coordinated / concerted, which is illegal.
If only 20% of volume in FX is speculative, then sites like Investopedia and Wikipedia have got it terribly, terribly wrong, because they state that about 85% of Fx volumes are speculative. I'm "just saying": your premise, here, may not be quite right.
As Xela stated, you may be basing your question on incorrect information. Additionally, your assumption that speculative volume is required for patterns to form is truly questionable. If that were the case, there would be no patterns in investment grade stocks, would there? But there certainly are patterns in such issues. Patterns are formed by changes in supply and demand, and not the nature of the volume. If the BOJ is buying USD to weaken the yen, or a million grannies in Iceland are also buying USD to put away for their grandkid's college education in the U.S., what's the difference? All that counts is the effect the buying and selling has on the supply and demand balance which will determine the direction of prices.
Even the non-speculative volume is actually speculative beyond 1st layer of trading or price action. Ex: A multinational company calls the forex broker to convert $100M from USD to GPY as they are buying a firm in London. The order is not speculative in sense that player is not betting on rise or fall of the currency but merely converting it. However, beyond this layer the order is speculative in that company is betting on the higher price of the firm it is purchasing, down the road like in 1-2 or more years. This way factors of supply and demand effect the prices of the traded instruments, as someone already mentioned it above.
Retail Forex trading probably does not even register on the radar screen - after all this market is traded by global banks, central banks, & corporations. The Forex market is $5,000 billion. Some retail clowns are nothing more than couch change in the worlds money supply. Individual Investors (source Investopedia) The volume of trades made by retail investors is extremely low compared to that of banks and other financial institutions. The Forex Market: Who Trades Currency And Why http://www.investopedia.com/articles/forex/11/who-trades-forex-and-why.asp#ixzz4vVq7b0RK The chart patterns are created by the sum of all participants - simple as that.
It's mostly PD's trading back and forth. Not really a structure, except to them. I've seen it and worked on a desk, it's mostly just manipulating into favorable positions.
Everybody is riding the coattails of the next larger level of trader, everybody is looking for a favorable entry no matter their time horizon, shorter term are eyeing the exits before they enter, market players' opinions are changing all day every day.. patterns form up