This is a short video summarizing papers r<g? and (better) section 6.4 of Fiscal Theory of the Price Level. Do low interest costs on the debt mean the government never has to pay it back? If the government doesn't have to repay debts, why do any of us citizens have to repay debts? Let the government borrow, pay off our student, mortgage, and auto debt. Let it send us checks and we can all stop working, paying taxes, and just order things from Amazon. Hmm. Something is wrong here...
The main point. We have 5% of GDP primary deficits, and bigger coming. A r<g of 1% is a fun possibility for government with 1% of GDP deficits and 100% debt to GDP. But it still leaves us 4% in the hole, and then the next crisis, pandemic, war, or social security and medicare come along.
Kudos to the Hoover Policy-Ed team (This video on their website, with additional material) and especially Shana Farley and Tom Church, who managed to boil down a complex subject to an understandable video. The animations are impressive. Yes, the guy talking needs acting lessons (it's a lot better at 1.25 speed) and a haircut. Next time...