There are two different kind of “prediction” mixed up here.

The thing which was easy to predict is that Trump is going to continue his trade war against China. It is also easy to predict that in a trade war companies who manufacture some product in China and sell it in the USA will suffer.

That prediction is enough for one to stay out of that kind of business. But it is not enough to do trades and profit from it.

If you could predict that Trump is going to announce x tarrifs on y tomorrow at z time that is much more likely to lead to succesfull trades. That is hard to predict.