If you have 10 bitcoin and lend them to me by giving me the keys and report that wallet as your bitcoin, and in exchange for lending me those, I give you 10 Wor

If you have 10 bitcoin and lend them to me by giving me the keys and report that wallet as your bitcoin, and in exchange for lending me those, I give you 10 WorthlessCoin as collateral, you now could say you have 20 bitcoin worth of holdings on chain, if you were playing loose with accounting rules. But in the end you might have 0 of anything if I go bust (and lost the bitcoin you lent me first) because of our off chain contract/loan. Dangerous waters.