Not necessarily. They’re worth 100B still, but they require the purchaser to “lock up” their capital. If you need liquid cash now and potential buyers are only interested in locking up their capital for higher gains/rewards, you might consider selling at a loss.

Yes, and if you hold it for the 10 year term, you do get the money back, plus a small amount of interest. The problem is that now, you can buy bonds with a shorter term that provide higher interest rates. Thus to sell the old bonds now, you have to sell them for less than you paid for them so that the return on them becomes competitive with buying a new bond.

Okay that is clear, thank you.

No, if you have to sell your bonds with, say, 9 years remaining, you won't get 100B for them. Think about it, you paid 100B to get 10-yr treasury bonds paying 2%/$4 billion, annually. Now someone can go to a treasury auction and pay 100B and get 4%/$8 billion annually. Why would they still pay you $100 B for yours? They are obviously worth less.