But that's exactly what Trump wants to do. Cut the taxes of the wealthy and expect the middle/lower classes to benefit, it's the definition of wealth trickling down (except it doesn't).

The article you cited states that "Higher taxes on the rich mean that those people have less wealth to invest, donate, and spend, while the government has more for its purposes.".

When reducing taxes this simply doesn't happen because it relies on the wealthy spending their extra income within the US economy when in reality there are tons of leakages that occur. The government on the other hand are capable of making investments within the economy which stimulate growth.