I think the rise of private credit is a great story to discuss. Every major commercial topic you can discuss, from inflation and monetary policies to trade wars, will be quite broad in the sense of affecting almost everything in the global economy - if anything, I would say the rise of private credit is a slightly more niche and finance-focused topic. The fact they are quite broad does not mean that you should not discuss any of them. The trick is to narrow down the scope of your analysis: instead of saying 'I will discuss the causes and effects of the rise of private credit', which commits you to an impossibly comprehensive presentation, you can state you will discuss one or two of its major impacts, the way it is affecting a particular industry, or its connection to the law firm you are applying at.