I'm not convinced that a 50% tax would actually be enough to afford a basic income for the entire population. It would also have to cover all other government expenses, and many countries already end up with taxes that approach or exceed 50%.
Consider also that the proportion of people who actually earn an income in many countries is falling already due to ageing of the population. Plus once this guaranteed income is available, it's only going to encourage more to give up working. Personally, I have already given up, even though my available income is substantially lower than the $2800 in the Swiss proposal, and really only covers my basic living expenses. Nevertheless, I value my free time highly enough that I prefer it this way.
> many countries already end up with taxes that approach or exceed 50%.
I doubt they're that many. Can you give any examples? And in the cases they do, most will be for an exceedingly small number of people.
Even countries people like to consider high tax, like Norway, does not get to 50% other than in extreme outlier examples (if you're an extreme high earner with a shitty tax accountant, has no debts or other means of getting deductions, and spends vast amounts of your money purchasing highly taxed items like alcohol and luxury cars).
If you mean marginal tax rates, then it's a different matter.
But I'd be pretty much nobody has an overall tax bill that approaches the marginal tax rate on their gross income. Norway, for example, has a marginal income tax rate that's 40%, but that only kicks inn on income greater than ~$135,000. Someone who makes $200,000 (about 3 times the national average) still only ends up paying 33% income tax total before deductions. Let's say said person spends $50k/year on stuff that's VAT rated at the full 25% rate (which is frankly unrealistic, and that only adds about 6.25 percentage points to their tax rate, bringing our example person close to 40%.
But if said person pays substantial debt interest (say on a mortgage), they'll also have massive deductions - it'd be fairly unlikely for a person at that kind of income level to end up paying more than about 35% between income tax, VAT and other taxes.
The rates reach 45% in Australia, and I suspect much of Europe is something similar. France was proposing 75% recently. It's true that these are marginal rates.
But consider how much taxes would need to rise to pay for the basic income. Let's say 50% of people who are eligible for basic income actually work. Then you'd need to collect two times the basic income from each of those people, on average. Surely this would push marginal, and probably overall, tax rates over 50%. Tax rates this high are only going to encourage even more people to give up working. I suspect such an economy would simply collapse.
It's possible that invention of Star Trek replicators would change things. If people could have all material things they wanted with minimal effort, then I imagine that the remaining work could move to a volunteer model.
Consider also that the proportion of people who actually earn an income in many countries is falling already due to ageing of the population. Plus once this guaranteed income is available, it's only going to encourage more to give up working. Personally, I have already given up, even though my available income is substantially lower than the $2800 in the Swiss proposal, and really only covers my basic living expenses. Nevertheless, I value my free time highly enough that I prefer it this way.