There's no way to guarantee. As a rule, the first generation earns a fortune, the second generation increases, and the third generation loses. Of course, there are exceptions, such as families that have maintained wealth for centuries, but in general, the law of three generations always works. Although at the same time, inequality is growing in society, as well as the proportion of those who inherited wealth. However, the latter is due to the fact that in most cases it is not the heirs themselves who manage this wealth, but professional managers. By the way, it seems that Winston Churchill is credited with the phrase: "From wooden shoes to wooden shoes - the journey of four generations: the first generation makes money, the second generation multiplies it, the third generation spends it, and the fourth generation goes back to the factory."