Fixed-income investment in a low interest-rate environment
Your assumption that low interest rates will "eventually" have to rise is not warranted.

Indeed, we are currently witnessing prolonged periods of low interest rates that do not obviously seem to be coming to an end.

Example 1. For 7 years, the US FOMC's target federal funds range remained unchanged at 0–0.25% (from Dec 2008 through Dec 2015). From Dec 2015 through Oct 2018, there have been 8 increases so that it is now 2.00-2.25%. But even after 8 increases, this rate range remains historically low.

Example 2. A more dramatic example is the case of Japan, where the 10-year government bond yield has remained closed to 0% for two decades now (and indeed is under 0% now).

You predict that since interest rates are so low now, they must rise. You might very well turn out to be correct, but this is hardly a certainty and there are many others taking the opposite bet.