Given the wealth distribution of the population has become so unequal, raising taxes for the purposes of lowering the deficit is a politically impossible option. So the only politically feasible option is controlling spending.
I'd like you to spell out your thought process, because I completely disagree with the relationship between your given and your conclusion, and I'd like to know what you're thinking.
It is generally accepted a wealth tax will not directly meaningfully lower the deficit. There's also examples of those who would be affected spending massive sums of money lobbying against such taxes and threatening capital flight. These are generally the same group of people as political donors.
Studies also show 84% of people across the top 36 major countries believe wealth inequality is a problem in their country. This leads me to draw the conclusion that politically popular tax policy and wealth inequality are closely intertwined.
All these things considered, a political party evaluating the risk of policy changes on their polling would always pick the option of reducing spending.