Wow, this is just entirely wrong. Completely and utterly wrong.
Sweden has a maximum of around 55% income tax bracket if you're in a municipality with high income tax, but billionaires never are and as such would be taxed probably at most 50% income tax bracket.
This is of course entirely irrelevant because billionaires don't make their money on income. Sweden has fairly low capital gains taxes - 30% on regular accounts, and a special account that taxes the whole account value by a low percentage, which shakes out in average years to even lower taxes on capital. This assumes you even keep your capital in the country, which is a big if.
There's also no inheritance tax, no gift tax and no property tax. Sweden is actually an unusually good place to be a billionaire as far as taxation goes, and a below average place to earn a high salary as far as taxation goes.