Any single individual with less than $12M (or a married/surviving spouse with over $20M) is not going to pay a penny of gift or estate taxes so the discussion exclusively involves high wealth individuals.

Within that subset, loopholes about for Trust Fund babies with significant inherited wealth that has never been taxed and decades to plan to avoid paying any taxes as funds are already planned to move to future generations before they are even born. However, the new money that was earned by someone not born to significant wealth is taxed at high rates on the way in over a lifetime until the income begins to primarily arise from capital and then it pays high rates again with estate/gift taxes as funds are transitioned later in life or upon death to the next generation. The system is literally the worst in terms of providing loopholes to people who are not necessarily producers in society (just born filthy rich) and holding the highly successful people who came from modest means over a barrel.