A money manager might say, she will invest your money in gold to preserve your wealth. She asks for a 0,5% fee per year and you pay the Dutch government 1,3% taxes per year.
If you have tens of millions and buy 500kg of gold, you will lose 1,8% per year. Your expected return is 0,98 per year. So after 50 years, how much gold do you have left?
500kg x (0,982)^50 = 200 kilograms, more than half your wealth is gone...
If you invest the money in assets that create cash flow, a (volatile) after tax, after inflation return of 5% is reasonable. How much gold will you be able to buy after 50 years?
500kg x (1+0,05)^50 = 5 750kg
You will have roughly 30 times more gold than in the option where you wanted to preserve wealth.
See also Matthew 25:14-30