That a product is harmful in and of itself is not evidence that there is an incentive to harm or kill the customers on the part of the companies selling it. Do you really think Marlboro or whoever wouldn't prefer to have their customers live longer, and thus purchase more cigarettes, than to have them die early?
You're not listening.
Marlboro knows its product kills; inasmuch as that removes customers, it's a
cost. It also knows it can hook X number of new addicts; that's a profit. And even in the customers it loses it can suck their dollars for 40-50 years.
Profit outpaces cost. That's all there is to it.
In the case of Thalidomide, more to the point of the thread, between 10,000 and 20,000 births worldwide were sabotaged by a drug put out to make profit for Grünenthal. 2,000 for example in the UK. The drug was never sold here. Why not?
Because the FDA, a federal agency whose job it is to screen such dangerous drugs, did its job and kept it off the market saving thousands of ruined lives. That's what the agency is there for.
That's not an incentive the drug company had before putting it on the market.