There is a big "Republicans are good for the economy" myth, which actually conflicts with the numbers. When you look at the economic performance during Republican and Democratic administrations, they mostly go down for Republicans and up for Democrats. Republican policies tend to exacerbate income inequality, which hurts the overall economy. Trump's tax bill is a huge example of redistributing income. Laffer is ignoring that, because the only income redistribution he worries about is from rich to everyone else.
I just did my taxes and made out very well because my wife and I have four different Qualified Businesses. I also did my 92 year-old mother's taxes and she got screwed. She's burned through her savings and has to sell her house to pay the assisted living bills.