My plan was a monthly subscription box of tiny socks for cats. My research consisted of one very popular video of a cat in socks. I ordered 300 pairs. It turns out cats do not want socks. Cat owners, after one attempt, also do not want socks. I sold eleven boxes, nine of them to relatives, two of whom have since stopped answering. I now own a great many very small socks and a scratch on my arm I think of as my only business card.
You found a gap in the market. The cats had already looked into it and passed.