The whole point of Bitcoin testnet coins are them to be worth nothing so you can test with them. You shouldn't be able to sell them, I don' think that's the point.
But loaning tBTC is different from selling it. While loaning tBTC itself it very controversial, there are few acceptable excuse such as preventing tBTC usage to claim altcoin/token and there's cost to mine tBTC.
I sent 2.06702067 testnet bitcoins over to @mocacinno - if you head over to the
Lending Section, you might be able to make a case for lending a large amount (providing you offer up collateral in exchange).
Given testnet bitcoin and Bitcoin Cash have a near identical logo, I'm wondering what the sudden interest in testnet bitcoins is?
Aside from what @pooya87 said, it's not sudden. It already happens at least 1 year ago, few
possible example
https://bitcointalk.org/index.php?topic=5262717.0https://bitcointalk.org/index.php?topic=5286384.0