I got my U.S. visa denied in late January, and today I reviewed the DS-160 form I filled out.
It seems that there might be several reasons for the denial:
Being older and single, with travel history limited to Asian countries and no records of traveling to Europe or Australia (likely a significant factor).
Having a U.S. ITIN (Individual Taxpayer Identification Number) and a lost passport record (suspicious).
Having a long history of credit in the United States (more likely to overstay).
If the last two reasons are the cause, it seems like I might not have any hope in the near future.
It looks like I won't be considering visiting the United States for the next few years.