The reason why debt is valued more highly than equity, thus giving off a smaller yield, is because of its higher ranking in the seniority chain. If the company fails to pay interest and principal according to the terms of the debt agreement, then the debtors will usually be able to take some equity stake in the firm after a bankruptcy proceeding.
The tip of the day is not to invest in an entity where it is mandatory for the existing equity owners to maintain control of an organization in order for it to operate. The leverage the debtholders have in such a situation is precisely none – if they force the organization into bankruptcy, they will be left with nothing, while if they do not, they will still be left with nothing except a promise to be paid.
A debtholder needs more than a promise to be paid – they need the ability to force the company into bankruptcy or liquidation if a default occurs.
That is brutal.