As I understand it, capital gains tax is applied just to the difference in price between acquisition and disposition of an asset. I picked gold for my example because it’s static, and the closest thing to neutral—compared to a business or even a productive asset like farmland.
If your business earns more money over time, I don’t think that’s a capital gain, strictly speaking, but rather profit. There are taxes on profit as well, but those are distinct from capital gains taxes, AFAIK.
I’m not an accountant nor lawyer, so this is just my lay interpretation, and I could be overturned by an expert in such matters.