Along with any reputation built up with that name. The long con, a la Pirate, is a problem, but few will have the time to invest in something like that, and no pseudonym is perfect. Just ask Trendon Shavers.
Have you ever lived in a developing country where there is no effective market regulation (not like in Singapore or the US or even Silk Road for that matter)?
Bascially, every non-repeated txn involves either a) swindling the swindler b) being swindled. Swindling is a contest of wits. It is a big waste.
Okay you say, just make repeated txns. Well what if I want to leave my village? Then what the fuck do I do?
Okay, maybe I come from an important town or ethnic group. My town or ethnic group has enforcement associations in other communities. They will help mediate my txns. Then I can do business elsewhere.
What if I'm not lucky enough to be born somewhere important? Should I just farm my plot and stay in my village?
This is how markets were organized in China prior to the 20th century by the way. Private, nonviolent enforcement of contract law through reputation. It limited long-distance trade to people originating from a handful of famous communities. Shouldn't everyone have the right to be an entrepreneur? Why set up such an unfair playing field?
[Don't get carried away here. The state still enforced criminal law and tax payment. They just did not think commercial law was the state's business. The standard interpretation is that lack of state intervention in Chinese commerce helps explain why Western countries got rich first.]