In Europe, most wealth is inherited, and power in concentrated in family dynasties.
If you have, say a $200K minimum threshold to start owing minimal annual tax, and a progressive scale after that, do you really think it would stop the next Bill Gates?
Why would anyone, including Pickety, want to prevent Bill Gates?
We should be trying to discourage the accumulation of power as well.
A person earning 40k per year isn't MUCH better off than the other. They are both broke, and only have money for the necessities. But if we only tax consumption. The person earning 10k will end up spending a larger percentage of their income in taxes than their counter part.
Now lets throw into the mix, me. I make a healthy 6 figure salary. Lets say I also only pay for what I use, and as a penny-pincher, I only get cheap housing, buy bread and cheese for my food, and tap water. I'm now paying the same taxes as the person earning an order of magnitude less than me.
Do you know many people with high incomes but super frugal lifestyles? If so, are they a rare counterexample, and not the norm?
Most every person I knows spends in line with income.
1. Rainy day fund, because you know one day the high pay may stop.
2. Retirement, because you know one day your ability to work may stop.
3. Estate planning, so that your family will be set up for a life that was better than the one you were given.
4. Investment capital, so you can turn your 100s of thousands into 10s of millions or more.
5. Startup capital for a future venture.
The difference between the middle class and the high-earners are that the high earners save their excess income.
1. You spend the savings, and pay consumption tax
2. You die, and pay the estate tax.
A consumption tax is always regressive.
More likely, we would heavily tax goods that poor people cannot afford. Things like dining out, travel, fashion, electronics, cars, and housing in excess of basic sq footage.