It’s kind of the human condition. Not being in control enough. Wanting those outcomes. So wanting power not (initially) for its own sake but as a means to an ends. But that’s what power means. An ability to have the outcomes you crave. To want stuff, to have the outcomes…
You can say dissapointed;
Think about it formulated as “Disappointed with how things are and wanting to do thing about it”. Disappointed sounds powerless but it’s an expression of feeling thwarted and hence wanting power.