What yo said.
I’m actually a full-time freelance Industrial Designer, and I’d say that 55-65% of my time is spent designing. The rest is customer calls, meetings, dealing with factories, accounting/taxes, collecting $, etc, etc, etc.
I couldn’t imagine if I were developing and selling my own product under my own brand. Shipping, packaging, marketing, branding, graphic design, writing copy, sales, even more meetings. Heck, I’d guess 1-5% of your time would be designing, the one main thing you’re supposed to be an expert on.
Focus on ID (your expensive degree), then feel it out from there.