In the Netherlands (where I currently reside as well) I think this tax can easily be avoided by placing your assets in some sort of shell company. When the startup I used to work for IPO'd I was not surprised to find that most of the important stockholders were using such companies (presumably) to avoid being taxed on their hundreds of millions/billions of euros.
I know that the Belastingdienst is going after people pretty hard for tax avoidance/evasion at the moment. Things are changing quite quickly in this area in the EU, and NL is no exception. What worked well for people 5 years ago could well result in a pretty full on audit now leading to nasty bills to pay back owed taxes.
The only problem is companies like Amazon, Google etc. are still getting away with paying 0 taxes everywhere... easier for the Belastingdienst to take on SME's first I guess. :/
As soon as you get it out of there either as income (at least some part is required) or as dividend and you start paying taxes. Not before so this is allowed and legal (and smart). They are about 25-30% in total well below the top tier of about 52% in case of income tax.
