The majority of US debt is held by entities within the US itself. About 39% is held by the Fed. The Fed is legally mandated to send all profits right back to the Treasury. So 39% of the government's debt will eventually be paid right back to itself in the future.
About 38% of US debt is held by US entities besides the Fed (banks, mutual funds, etc). If the US defaults on its debt, these financial institutions would immediately fail, as their asset base would be worth far less than their liabilities. Everyone's savings would be immediately wiped out.
About 23% of US debt is held by foreigners (mostly central banks of other countries). If the US were to default, these central banks would also have a hard time staying afloat. The economic effects would quickly spread worldwide.
Finally, the US dollar would tank, meaning that even if you had all your savings under your mattress and never used the financial system, you would still be screwed.
So, does anyone actually win? Well, US sovereign CDS holders win (assuming they can even get their counterparties to pay up). The US government gets a temporary win at the expense of its citizens, but it's extraordinarily bad in the mid-long term.