Debt is the right metaphor. Some amount of tech debt is virtually unavoidable; just like w/ $, a low-interest student loan or mortgage might be a great investment, while using a high-interest-rate credit card, or usurious payday loans, represent catastrophe. Cutting a few corners for the sake of GTM is often the former. Forgoing proper tests, or letting PoCs shape architecture, is more like the latter.

I don't see "swimming" replacing it anytime soon -- and the energy you'd expend trying to shift the metaphor might be better spent elsewhere.

That said, "swimming in debt" still works, as a fairly common and intuitive metaphor. Break-even is treading water, profitability is flying above the waves, and accruing debt can put you in Davy Jones' locker.