Thoreau isn't celebrating poverty or asceticism for their own sake—he's pointing out that refusing what you don't need is a form of power, not deprivation. Most people assume wealth means accumulation, but he recognizes that a person who can walk past the expensive car lot unbothered, or decline the promotion that demands their soul, possesses a freedom that money alone can't buy. A billionaire tormented by the need to acquire more is actually poor by Thoreau's measure, while a modest person content with enough has become genuinely rich.