that s what a trendline is, just a point of view, if you could draw all of them on a chart well they would all look good, because people are following them, it s like driving on roads and following signs. everyone agrees they are good to follow so everyone gets where they want.
well said, mighty jol
I'd like to add:
it's like the apparent hard bottom at 400. it's just an arbitrary number, but there appears to be a large amount of support at that level. Does support show up at that level organically? possibly, for the first time.
the second, third, forth times... likely are bolstered by people that like to read lines.
when the lines are false (probably a 50% occurrence) or even when they're true, they will be broken. the great benefit that they can provide is that they might leak a sneak preview into what might happen when the trendline is broken.
the lines cannot predict the price, they can only help
you to predict the price.