Bank companies issue bonds mainly to replenish capital. For example, due to the 7.5 trillion credit granted last year, the bank's capital adequacy ratio is less than 8%, and the core capital ratio is supplemented when issuing bonds. Generally speaking, the international proportion is above 4%. Capital adequacy ratio = own capital/total assets =8%, and more loans will inevitably mean more deposits, so the total assets (liabilities+owners' equity) of banks will increase.
Insurance companies issue bonds to increase the ratio of compensation to capital, which is similar to the reserve ratio of banks (insurance is not familiar ~ ~).
It depends on what kind of bonds are used to adjust the capital structure and implement the future strategy for a long time. Adjust funds in the short term to solve the problem of tight funds.
Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.