It's possible the price is too high, but the reason it has that price $35/bottle is the minimum required to sustainably produce it. It's well accepted in economics that price of manufacture is not necessarily the societally optimal price [0]. If this is the case, what needs to be done is government subsidization, and no individual person can just start a company and do it themselves.

Also, the idea that everyone is free to start manufacturing insulin ignores the billions of dollars of capital that is required to create a FDA-compliant insulin production plant, which almost no one on earth has access to.

[0]: https://www.investopedia.com/terms/e/externality.asp