Trendline /dynamic Trendline breakouts, why reversal?

If you have a trendline or dynamic trendline (moving average line), and price touches it a few times , it is said to be trending nicely . now if price breaks through, we say a reversal is predicted . this means that a reversal is more likely to occur than e.g. sideways trending, or less steep upward continuation trending. why is the reversal path more likely after a breakout? (see pic). just don’t understand why we predict a reversal to occur after a breakout. same question too for a dynamic trend line.