Is your 401(k) in USD? Or am I missing something?

I think that depends on what effect you think the collapse would have on the market and economy.

If US cost of debt goes up, then you would either have cut spending, or raise taxes and spend a greater portion of budget on interest.

Neither of those are particular exciting for long term business growth.

Low interest rates on US public debt boosts spending and the economy. No matter if you think the government spends money in a wise or efficient manner, it is better to do so with low interest than high.