These very wealthy individuals, more like institutional investors in nature, usually hold high-grade corporate debt. A very small amount of low-grade bond is in the hand of individual investors because bonds are downgraded as a result of declining corporate performance. From a logical point of view, QIBs and OTC are the defining features of corporate bond market.
If we fail to follow this logic, things will get problematic. The third is about environment. Corporate debts need an appropriate eco-environment, which includes institutional set-up, such as good laws and regulations (that provide clear legal definition), an improved accounting system (that provides all the necessary information to investors without misleading them), regulation of information disclosure, and improved bankruptcy law, etc.