I don't think that anyone argues that rich people don't spend money in the local economy. The question is whether giving them more money means more spending in the local economy compared to giving more to the poor or, say, spending it on infrastructure projects.
Would giving $100,000 to Bill Gates result in more economic stimulus than giving $100 each to 1000 poor families ? Is maintaining or building transport routes - which can give long term benefits to businesses that use them - in addition to the money going to the construction firms and their workers, obviously worse than cutting taxes for the rich?
It doesn't seem obvious that trickle-down is even plausible, let alone definitely a good idea.