The market value of all US corporate IG bonds outstanding has increased from $3 trillion in 2010 to $9 trillion today, see the first chart.
Over the same period, the private credit market has grown by $800 billion.
The bottom line is that public IG markets have since 2010 grown eight times faster than private credit, see the second chart.
In short, when discussing growth in private credit it is important to also consider the growth in public credit over the same period.