To answer your question directly; working at a VC firm as an analyst does little for you to understand how to run a business. Conversely, any startup should start with four fundamental pillars of foundation: THe Architect (CEO), The Money Guy (CFO), The Hustler (Sales), and the Techy(CTO).

To directly correlate with your question, entrepreneurs should be well versed in many aspects of their business. Often, many newcomers believe that knowing just one skill will suffice, which is not true. In the case of your question, I would suggest marketing/sales be your priority(since every entrepreneur can benefit from the learnings, and quickly make them actionable within their own business).

To Indirectly answer, entrepreneurs should always learn new skills and build not only their skills toolkit but also their mindset. I hope this answer finds you well. Best of Luck with your endeavor.