Bonds of any type are investments for gullible people that are buying the illusion of a guaranteed return. Those people generally have such little financial sense that they don't even realize the resale value of their bond will drop when interest rates rise. Best case for them is their returns manage to be slightly better than the drop in the purchasing power of the eventual return of their principal. The drop in purchasing power is inevitable as inflation continues to degrade it.
When interest rates rise (a safe bet right now considering the relatively low rates nowadays) suddenly they find their guaranteed return looks pretty weak, and the only way out of their investment so they can get into a higher rate bond is to sell the original one at a loss. Either that or continue to hold it and have the buying power of their principal eroded by inflation year after year.
The only reason I wound up owning that bond I had way back when was that I was following the advice of a financial advisor, who as it turned out had a financial incentive in getting people to buy those bonds.
Bonds have been a particularly poor investment this century, as have Treasuries. In the old days, they were useful in having a balanced portfolio - safe bonds, with a moderate return to preserve assets and generate cash flow, balanced by a mix of stocks for income and growth. And, if one was really rich, real estate for the third leg of the table.
With the communists in charge, no bond you could buy today has a chance of keeping up with inflation. And as you noted, selling them as interest rates climb will just lock in capital losses.