I mean it is not possible to ascertain when a trend starts and much harder when it ends.

Have an extreme example of this Fed.

When the Fed decides to raise rates by 1 percent they know that this decision will have a huge impact and that the EURUSD will decline sharply, but the Fed will be not able to forecast or will be completed this fall (thus the end of the tendency in court)

the launch of a trend is not random, it is only unpredictable and finish of a trend more.

When we are able to ascertain the start of a trend and its own end, therefore we are billionaire because it means we know the course ahead.

We just have a probability that the trend continues we believe that this is all:-)