פירוש על קידושין 63:6

That he takes a purse, etc.: And if you say the honor of the father that is upon the child [that involves] monetary loss is only [taken] from the father - if so, that purse that Rabbi Eliezer spoke about is the father's. So what difference is there to the son, [that he would] embarrass him?

As we have seen before, the height of honoring one’s parents means watching the parent throw away a purse of money into the sea and not shaming the parent. But if the parent has to pay for his own upkeep, then it really does not matter, because the financial loss is the parent’s loss. So its not such a great show of honor to not get angyr.
The answer is that it does matter—if the child will inherit the parent. In essence, the parent’s current loss is the future loss to the child.
This section does acknowledge an inherit tension between parents and children, one that still exists to this day. Currently, the parent’s assets belong to the parent and the parent can dispose of them at his/her will. However, this money will eventually go to the inheritor, usually the child, and if the child is taking care of the parent, and in some ways has authority over the parent’s money, the child may be hesitant to spend it, especially if he perceives the spending to be frivolous.