Another way to see it is that physical $100 has $300 of value.
But eventually, Alice wants her money back, the bank cashes in the bond, the government repays the cash.
So part of that value is the value of trust as a function of time. Trust in the bank, trust in the government, trust that they'll pay back their debts on a defined schedule. Plus interest.
Yes, stacking money is based on trust. Realistically, a 6-month $101 government bond which costs $99 should be valued about $100, and a bank deposit stacked on $101 of government bonds should be worth about $100, as long as trust in those continues to hold. And this sort of thing does happen in cryptocurrency systems. Stablecoins generally trade for a fraction of a cent less than their corresponding fiat currency. Bonds may trade for more, if the promise of interest is accepted, but less than their redemption value.
But eventually, Alice wants her money back, the bank cashes in the bond, the government repays the cash.
So part of that value is the value of trust as a function of time. Trust in the bank, trust in the government, trust that they'll pay back their debts on a defined schedule. Plus interest.