Trust

https://www.forbes.com/sites/jayadkisson/2012/08/25/trust-protectors-wha...
There are lots of ways to do this, but the #1 best and leading way for trustees to milk fees is to manufacture a dispute with the beneficiaries -- this leads to litigation, and litigation leads to fees.
There are other benefits to such trust litigation, such as that the trustee can hire a law firm to help milk the trust and the trustee can sometimes receive "referral fees" from the law firm around-the-barn or at the very least the law firm will be expected to send its new trust business to the trustee.