Can the Dutch Tax Authorities show me where I can with relative safety make 5% ? my 5 figure portfolio (uk) returns about 3.4% income. Its also odd that if say

Can the Dutch Tax Authorities show me where I can with relative safety make 5% ? my 5 figure portfolio (uk) returns about 3.4% income. Its also odd that if say you get a ten bagger and turn 5k into 50k for a 45k capital gain you don't pay tax on that capital gain. It would make sense and be firer to tax income and capital gain different and on actuals.