Collecting the FIFA World Cup sticker album presents a classic public-goods and collective-action dilemma, in which completing a collection on one's own is highly inefficient. To evaluate how localized community norms shape collective efficiency, we use agent-based modeling and Monte Carlo simulations, parameterized with empirical field observations from exchange meetups in Natal, Brazil. Reflecting the tournament's recent expansion, the Panini 2026 album features 980 individual stickers, including 68 metallic specials. We contrast a standard baseline economy (1:2 special-to-normal exchange ratio) with an overprotective, strict strategy (exclusive special-for-special trading) and an altruistic, generous strategy (in which advanced players surrender needed duplicates to assist peers). Our findings reveal that overprotective rules trap liquidity and drive network-wide inefficiency. The strict strategy increases median completion costs by 10 packs and severely penalizes the least fortunate 5\% of collectors, adding 20 packs in large cities and 30 in small communities. Conversely, widespread generosity optimizes network liquidity and dramatically compresses the long tail of bad luck. Introducing the generous strategy reduces required purchases for the 5th percentile by 90 packs in large-scale configurations and 130 packs in smaller clusters. Furthermore, widespread altruism triggers a strong functional coupling that effectively synchronizes completion rates across the network. This study demonstrates that while rigid, protective norms degrade collective welfare, generosity successfully mitigates pack-draw variance, transforming an expensive, isolated hobby into a resilient, highly efficient public good.

翻译：收集国际足联世界杯贴纸册是一项典型的公共物品与集体行动困境，其中个人独自完成收藏极其低效。为评估本地社区规范如何塑造集体效率，我们采用基于主体的建模与蒙特卡洛模拟，并以巴西纳塔尔市交换聚会的实证田野观察数据作为参数。反映赛事近期扩军，帕尼尼2026年贴纸册包含980张单独贴纸，其中68张为金属特殊贴。我们将标准基线经济（特殊与普通贴纸1:2交换比率）与过度保护型严格策略（仅限特殊换特殊交易）及利他型慷慨策略（资深玩家放弃所需重复贴纸以帮助同伴）进行对比。研究结果表明，过度保护规则会套牢流动性，并引发网络级低效率：严格策略使完成收藏的中位数成本增加10包，且严重惩罚最不幸的5%收藏者——在大城市增加20包，在小社区增加30包。相反，广泛慷慨优化了网络流动性并大幅压缩坏运气的长尾效应：引入慷慨策略后，大规模配置中第5百分位所需购买量减少90包，小型聚落中减少130包。此外，广泛利他主义触发强功能耦合，有效同步网络中完成率。本研究证明，刚性保护规范会损害集体福利，而慷慨策略成功缓解卡包方差，将昂贵、孤立的爱好转化为弹性强、效率高的公共品。