Anyone with collateral can go into debt at 3%(ish) interest. I've never heard of anyone getting a sizable loan for longer than overnight at that rate without collateral. If there is a counterexample please share it. And if a person defaults on a collateralized debt, well, they lose, and usually badly. Margin calls are one of the nastier examples, but foreclosures also come to mind. Even a safe investment like US Treasury bonds can trigger a margin call if, for example, interest rates rise and reduce the market value of the bond enough to fall below margin requirements.

Most vanilla corporate bonds are unsecured and offer nothing more than a promise not to give anyone else security over the corporate assets and an unsecured debt claim.