Wealth, once acquired, is far easier to lose than to retain or grow. There are plenty of families who were wealthy once upon a time but are no more. A few families have been lucky and found that although wealth has been dissipated through the generations every so often someone in the family does well and restores its wealth but this is not the norm.
A plan for wealth preservation starts by recognising it is a discipline - a family has wealth and it is to be preserved. This discipline, once recognised, has to be preserved - and through the generations - or wealth is unlikely to be preserved.