Why do Neo-Liberals like Trickle Down Economics? -What do the other forms of Conservatism think about this?

-Neo-Liberals Argue their policies like Little Taxes, Deregulation and so forth will lead to a 'Trickle-Down' Effect -If the Rich can keep more of their money, they can make more money, Employ more People, and Pay them better -Wealth will thus 'Trickle Down' to all Levels of Society. -This of course is another Abstract Idea and one that other Forms look with Caution. Where is its roots?