If you had a million dollars, would you use that money to buy a drug company and sell insulin at a very high price because a lot of people are diabet?

That million dollars wouldn't be enough to buy any company much less a pharmaceutical company. It would take more like 1 billion dollars.

Even a non incorporated company often costs more than a million.

Twitter cost Musk 44 billion BTW! Most pharmaceutical companies cost even more than that.

The whole pharmaceutical industry is worth 1.3 trillion.

https://montjoys.com/how-much-is-the-pharmaceutical-industry-worth/