the misconception and funny math start at the point where you "kept the other $1 for yourself."
that $1 is not yours to keep, and never was. it is a promissory note to repay, in this case to your parents. it is not an asset in your column, but a liability. a marker that represents an obligation to repay $0.5 to each of your parents. the $1 is, however, an asset in your lenders' column, no matter who is physically holding it. they issued it and they can demand it back at anytime (call the note), hence the notation "federal reserve note" emblazoned on top front of the fine linen.
so the math goes like this: -$100 from mom and dad, traded for a +$97 shirt, +$2 repaid to mom and dad, and +$1 due mom and dad held in reserve = $100. there's still only $100 of 'value' (if you can call it that) out there. the key is who is temporarily holding it. and when/how do they plan to settle the account.
you have a nice shirt (collateral) and a dollar (liability), your parents posses a debt instrument (asset) worth now $98. and if the issuer of currency decides to fire up the presses and give all the poor disadvantaged folks who can't afford their own shirts say $100 in stimulus to go buy shirts, then you can pay your parents back with the new notes.
that actually means that you now got two $97 shirts, mom and dad are paid off, and you have even more change left over (due to the federal reserve of course). but like all creditors, they at some point expect to recover their investment in your future, and when that time comes you may just 'lose your shirt', or shirts.
but because you enjoy the shirts (collateral) now, and had no practical intention or ability to repay the notes (debt) to mom and dad when you borrowed it, then who's the sucker?
burro econ 201.