SAN FRANCISCO—Four-year-old OpenSea has gained fame and a $13 billion valuation by staking a claim as the world’s biggest marketplace for some of the buzziest new items to trade, nonfungible tokens.
It has also become a haven for fakes and scammers trying to get users’ money or access to their newfangled assets—creating a struggle for the company that reflects a core paradox for emerging digital investments. On the one hand, enthusiasts are attracted to them because they are “decentralized,” operating largely outside the control of banks or government rules. On the other hand, when things go wrong, many of those enthusiasts expect OpenSea to enforce rules and compensate people who are ripped off—exactly the kind of role that centralized institutions have traditionally played.
NFTs became widely popular last year as a means to own digital versions of art and pop-culture…
