How does it work exactly?
The exact same way it is advertised, it gives the rich more incentive to invest their money to generate more return, which generates jobs for the less fortunate, improving their lot.
The trick is it doesn't work in a country full of super-rich people with massive income inequality, where lack of investment capital isn't an issue. It works if the conditions are right - if the income inequality is low and the potential for investment is hampered by high taxes. Then trickle-down economics can do wonders, just look at China FFS.
Once that bottleneck is cleared, tricke down economics don't work any more. That doesn't mean the policy is bad per se, just that it was utilized for longer than it was useful. Socialist countries did the same mistake but in reverse, extremely low income inequality in itself causes massive damage to the economy all by itself and policies that ensure it also cause obvious damage to the economy.
McHrozni