[Question] over collateralized borrowing

Could someone explain why this exists? I saw an example that read: "Consider the case where you own ETH and need liquidity, but you do not want to sell your ETH. You might consider collateralizing ETH in order to borrow stablecoins." Excuse my language but what kind of fucking problem does this actually solve? You want to sell ETH; fine - but because you dont want to "get rid of your tokens" you come up with this """ingenious""" idea to lock up your tokens which fulfills the exact same thing you were trying to avoid in the first place only to ON TOP OF THAT pay EXTRA INTEREST. In what world does this actually make any sense what so ever?