Trickle Down Economics Cannot Fail

they can only be failed.

The rich really are different:

Matt Yglesias considers, and rejects, the notion that taxes on the rich impede capital formation:

Remember, folks, Matty Y. exists for two reasons; to put a 'liberal' seal of approval on war, and to be a punching bag for the likes of Megan. And to be cited by otherwise good lefty blogs because he makes weak versions of common arguments for websites that get lots of hits. Bah. Anyway, Megan.

It sounds deep and smart when you call it "capital formation", and stupid and crazy when you call it "the rich uncle argument", but they're essentially the same thing. And it should be noted that many, even most, liberals believe that this is true--or at least, they used to, back when they were discussing the Bush tax cuts. At the time, the ground was thick with liberals complaining that it was a terrible idea to cut taxes on the rich during a downturn, because the rich save their money, while the poor and the middle class spend it.

Nope, I didn't fail to reinsert links. Shockingly, Megan is making this ludicrous claim without the slightest bit of documentation, because documentation doesn't exist. Matty Y. and Ezra agreeing to stop her spazzing out at the lunch table doesn't count.
The only possible explanation is Megan, being a movement conservative at heart, thinks the MSM talking heads promoting tax cuts that benefited them, and the people signing their paychecks, personally a great deal counts as a liberal anything. Of course, this is a woman who thinks complaining about how gender based pay discrepancies affect her personally makes her a feminist, so let's not pretend to be surprised.
*Update* - I shouldn't have written this so late. I have to be honest, I effed up and misinterpreted what she wrote. Somehow I morphed what she was arguing into a claim that some liberals were in favor of the tax cuts, instead of opposing them because of some bizarro half belief in trickle down theory. My bad.

Then or now, saved money is where all the capital that funds startups--or any other sort of investment activity--comes from.
Of course, if we will have a government, we are going to have to tax someone to fund it, and the rich have more spare cash in their possession than anyone else. But of course, when we tax the rich, they don't just cut back on their yachts; they also cut back on their saving and investment activity, which in the long run means that we will all be a little poorer. Life is full of tradeoffs that can not be vanquished with even extremely biting sarcasm.

I guess it's biting sarcasm to state that trickle down economics demonstrably don't work. She takes it as a given, which must mean it is one. After all, Megan is on the cusp of being a homeowner, and it's thanks to the charity of a rich person, so that would work for everyone if they'd just work hard as an ass kiss for a decade or so so, like she has.
The sad part is that last bit isn't really snark. It's quite possible she believes such a pile of mush. I've known heirs of name brand fortunes who believe they earned their vast inherited wealth with hard work. Never underestimate the capacity of a human mind to contort itself to avoid self-recognition.