Finland
Reported as business income (toiminimi), the earned-income portion taxed progressively to ~50-57% at the margin and a small capital portion at 30/34%. Mandatory YEL pension (~24%) applies. Not capital gains.
Self-employment / business income (elinkeinotoiminnan tulo), split into earned- and capital-income portions - NOT capital gains.
Earned-income portion progressive (state + municipal), combined marginal ~20-57%; a notional capital-income portion (20% return on net assets) taxed at 30/34%. Most falls in the earned-income portion.
Mandatory YEL entrepreneur pension ~24.1% of confirmed YEL income (min ~EUR 9,208/yr), fully deductible, plus health-insurance contributions.
Sole trader (toiminimi); 5% entrepreneur deduction; VAT above EUR 20,000 turnover (financial-service exemption may apply).
USDC is business income at EUR value on receipt; for a trader it is business income, not the 30/34% private-investor rules.