Quote from Martinghoul:
Ah, that's because you're disregarding the negative carry... Which is OK to do if you expect the blowup to occur tomorrow. However, if you have to wait a few years for the blowup to arrive, you're gonna die a death of a thousand cuts. JGB GC is <10bps, so for every year your 10y JGB just sits at 1% you lose 90bps in negative carry and 13bps in rolldown. 10y JGB yield has fluctuated between the extremes of 50bps and 200bps for the last decade or more. So you go short 10y JGB at 1% and assuming nothing changes, you could make max 100bps, lose max 50bps on a mark-to-market basis, but pay smth like 113bps/year for the privilege. One advantage is that the volatility of this position is likely to be low. Still does that sound like a good investment, unless, of course, you expect the blowup to happen very soon?