Tax wealth. I know that's a very hard thing to do due to the mobility and political power of capital, but we need international co-operation and just do it. That's where all the money is and where it's going at an accelerating rate.
The way this tends to turn out is that the type of assets accessible to younger/working people is taxed and the type of assets held by older/non-working people is not.
E.g. look at Ireland. Ireland has a de-facto wealth tax ("deemed disposal" - taxing the unrealized gains) on ETFs starting at the first euro, which makes investing basically pointless. Meanwhile it also has one of the lower tax levels on property in the EU.
Yes, it needs to be done in a fair manner. France used to have a tax (Impôt de Solidarité sur la Fortune) which was anybody with more than X millions of assets had to pay 75% of income tax. (I believe it was 10 millions, but I could be wrong) It wasn't perfect, but it wasn't a bad idea. IIRC it was slashed by Sarkozy right before the 2008 crisis as part of his campaign promises, and he just kept going with his tax cuts on the wealthy after 2008.
Another thing could be multipliers on property tax. For example, you would pay 0.75× of the property tax on your primary residence, 1.5× the property tax of your secondary residence, and start going exponentially on third, fourth, ... residence. Of course, there would be loopholes (like owning properties through companies), and these loopholes would need to be closed.
You could also tax buy-backs and dividends. (If a company buy their own shares, they have to pay a 50% tax on it)
There are a lot of possible implementations that could add up to each other. It's a fallacy to just point at the bad ones and say "look it doesn't work!"
The main issue is that there has been a transfer of global share income from labour to capital in the last 50 years. However we expect to pay for pensions just by taxing labour. It doesn't matter if there are less young people, because (as shown by GDP growth) they are producing more overall, but misinformed politicians use this argument because they don't understand that these folks didn't profit from the increase in productivity. We need to fairly take a share from this productivity increase and distribute it as pensions. The goal is to pay for what we promised, while relieving burden on young people.
Why would you limit to only billionaires, and why would you compare it to all spend? Try funding pensions and healthcare by taxing the wealth of the top 0.5% and it doesn't sound so impossible.
A realistic wealth tax probably caps out and around 2%, remembering that the net worth of very rich people is generally not liquid and can be difficult to mark to market. Any higher rate risks forcing the rich to have an asset fire sale, which liquidates productive assets and isn't really good for anybody. At six to seven percent you would force them to be entirely liquid and would begin to shrink their wealth, killing off the tax base in a few generations. Even this is absurdly optimistic since a globally standardized wealth tax is a pipe dream and without it you get capital flight as a result of any wealth tax at all, but let's ignore that.
To steelman this as much as possible let's say you can charge 6%. The top 0.5% are worth $30-$40 trillion in the U.S. (which is just an easy example because the statistics are available) which gives you a probably unrealistically high max annual tax revenue of $2.4 trillion. Social Security and Medicare in their current form cost $1.35 trillion a year; Medicare for All would double to triple that or more, depending on what estimate you believe.
Europeans pay for their social safety nets with very broad taxation while America instead charges negative income tax (after credits) to the bottom 60 percent of the population (even after inflation, excise taxes, state tax, payroll tax and tariffs the total tax burden is pretty slim at the bottom end by European standards). There doesn't seem to be a mathematically feasible way to give benefits to the working class that the working class doesn't pay for.
You're probably right, though U.S healthcare costs per capita are much higher than they need to be, and would be much lower in a "proper" single payer system like in Europe. In any case, a wealth tax would still help a lot with being able to fund these programs. Yes, the working class does have to pay as well, but it'd be much less if there were a reasonable wealth tax.
But yes, global co-operation to enable a large enough tax on wealth is not going to happen any time soon. A more likely scenario is that as automation develops and as the share of income that capital gets grows, the working class will end up in a position bad enough that capitalism will collapse and be replaced with something else. Hopefully with something better, but could also be worse.
And in Sweden, another "nordic socialist country", there's no tax on property nor inheritance, as well as very low taxes on invested capital. There are about 1.5x more USD-billionaires per capita in Sweden than in the US. I think there's room for some more taxes.
"Democratic Socialists" in America aren't socialists. Even Bernie Sanders doesn't advocate seizing the means of production. You can argue we use it wrong, but we can argue it's our language and we evolved it.
But I don't think even all the nominally socialist parties in Europe are really socialist either.
