Re: $1M a year — is that a lot?
Yes, tax is complicated. But this group are not trying to recommend how the government decides to balance sales, income, capital gains and wealth taxes (all of which already exist in some forms in every economy).
However, their one, simple slogan is perfectly reasonable, perfectly clear and indicates they exactly understand... "tax us (and the people who have even more than us) more in order to build a better and fairer society - experts can work out the details".
This isn't a US-only problem. I, and many others, have long voted for political parties who would increase the tax I pay. I suspect many others here are the same (after all, tech generally pays well).