Drawing imaginary lines on charts with crayons for dummies? TA seems to mostly be astrology for finance.
If enough people believe it's true, it becomes true.
I don't use it currently, but I dabbled with it when I was younger (not as the only thing I looked at).
Financial markets, to a certain extent, can be manipulated by people. If enough of them believe that when the face of Jesus appears in the chart they need to sell, the price will go down.