A politician that gets all the votes because he is the only choice is powerful.
A corporation that acquires a monopoly and becomes the only choice is powerful.
The title of this post isn’t the definition you’ll find in the dictionary though a lot of definitions will mention influence, however, it means that the antonym of power is competition. Yet, that doesn’t come up in any thesaurus. Instead what comes up is:

None of these seem to fit to me. You’re not a failure just because you’re not powerful. You’re not inefficient just because you’re not powerful. You’re not inable just because you’re not powerful, nor are you incompetent.
Power is a story. A belief that there is no other option, however, in a world of infinite options there is always a choice if we can live with the consequences.
p,S, This topic seems to run deeper, like there is an essay here, so I’ll probably write one in the future.