A Yale study published in 2025 found something nobody in the sustainable fashion movement wanted to hear: people who buy the most secondhand clothes also buy the most new clothes. In fact, 59% of respondents reported high consumption in both categories. The virtuous circle of secondhand shopping—where buying used supposedly reduces demand for new production—turned out to be more of a consumption spiral.

When Thrift Shopping Became Shopping

The secondhand apparel market is projected to hit $350 billion globally by 2028, growing at 12% annually. That's fifteen times faster than traditional retail. Half of all consumers now shop secondhand, and Gen Z and Millennials spend nearly half their clothing budget on used items. These numbers get celebrated as proof that fashion is finally going circular, that we're breaking free from disposable culture.

But the Yale researchers found something more complicated. The people most engaged in secondhand markets weren't replacing new purchases—they were adding to them. Call it moral licensing: buying a vintage jacket feels so virtuous that splurging on a fast-fashion haul seems justified. Call it the rebound effect: when clothes become cheaper through secondhand access, people simply buy more total items. Whatever the mechanism, the result contradicts the basic promise of circular consumption.

The study revealed another uncomfortable truth. Demonstrating knowledge about fashion's environmental costs—the industry produces 2% to 8% of global greenhouse emissions, more than international flights and shipping combined—didn't predict sustainable purchasing behavior. People knew the facts. They bought more clothes anyway.

The Economics of Endless Availability

The secondhand boom rests on a foundation of overproduction. The fashion industry churns out 2.5 to 5 billion surplus garments annually, a 400% increase in clothing consumption over two decades driven by fast fashion. This creates a paradox: secondhand markets depend on the very excess they claim to solve.

Online resale platforms have industrialized what used to be informal exchange. The online segment grew 23% in 2023 and is projected to reach $40 billion by 2028. Platforms like ThredUp, Poshmark, and Depop turned closet cleanouts into side hustles—nearly half of resellers used their earnings to pay for essentials like food and bills. When 41% of consumers say secondhand is the first place they look for deals (50% for younger shoppers), you're not looking at a niche anymore.

This professionalization changed thrift stores themselves. What used to be community resources increasingly stock low-quality fast fashion that wasn't worth buying new and deteriorates quickly. Meanwhile, anything decent gets pulled by resellers who've turned thrifting into inventory sourcing. Trendy vintage boutiques then sell curated pieces at or above original retail prices, erasing the accessibility that made secondhand shopping democratic.

The demographics tell the story. Gen Z, with median income of $52,460, shops secondhand for personal style expression and deals. Gen X, earning $101,500, uses secondhand to afford luxury brands they wouldn't buy new. Both groups are adding secondhand to their consumption, not substituting it.

Brands Hedge Their Bets

Retail executives aren't stupid. They see 90% of their customers already participating in resale—an all-time high. So 163 brands launched resale programs in 2023, up from 124 the year before. Branded resale grew 31% year-over-year, and 74% of executives not yet offering it are considering the move.

The pitch is elegant: extend product lifecycle, capture more value per item, advance sustainability goals, acquire new customers. And it works—80% of brands with resale programs report generating more revenue, 87% claim progress on sustainability targets.

But here's what they're really doing: maintaining control over their products' entire economic life. When Patagonia or Lululemon runs your resale transaction, they're not ceding market share to thrift stores—they're expanding it. They get data on how long products last, who buys them secondhand, and what price points work. They keep customers in their ecosystem. And crucially, they keep selling new items to the same people buying used ones.

The Yale study suggests this might be exactly what happens. Brands offering resale don't cannibalize new sales; they increase total transactions. The customer who buys a used Patagonia jacket becomes more engaged with the brand, more likely to buy new Patagonia items later. Circular consumption becomes circular marketing.

What Regulation Misses

There are currently no policies in the U.S. or Europe regulating resale of secondhand clothes or requiring environmental impact disclosure. That absence matters because it lets everyone claim credit for sustainability without measuring actual outcomes.

When a jacket gets resold three times, is that one jacket replacing three new purchases? Or is it one person who would have bought one jacket now buying four total items because secondhand options expanded their access? The Yale data suggests the latter, but nobody's required to track it.

The fashion industry's environmental damage comes primarily from production volume, not just disposal. If secondhand markets enable higher total consumption—more items per person, faster turnover, expanded participation—they could increase environmental impact even as they reduce landfill waste. It's possible to recirculate more clothes and still generate more emissions.

This matters for policy. Tax incentives for resale platforms, sustainability credits for brands offering take-back programs, marketing claims about circular fashion—all assume secondhand reduces new production. If it doesn't, we're subsidizing consumption growth while calling it environmentalism.

Beyond the Circular Myth

The secondhand boom is real, economically significant, and probably permanent. But it's not solving what we thought it would solve. The market hit $350 billion not by replacing fast fashion but by coexisting with it, often in the same shopping carts.

The solution isn't abandoning secondhand—it's abandoning the myth that making consumption easier, even secondhand consumption, reduces consumption. Real circular fashion would mean fewer total garments, longer use periods, and actual replacement of new purchases. That requires buying less, which no market participant has incentive to encourage.

Until someone measures whether secondhand shoppers actually buy fewer new clothes—and early evidence says they don't—the hidden economy of secondhand fashion is hiding something important: it's still just an economy, growing the way economies do, by selling more stuff to more people more often.