Is it reasonable to say in some cases the art killed the artist?

No, it isn’t reasonable. It is more likely that the art provided an outlet of expression that kept the artist alive longer than they would have dealt with the distress that ended things.

^^ I agree.

In some cases it was the ventilation and what was in the paint that could cause an early death.

Like the selfie photographers that fall off a cliff?

I read somewhere that one of the most famous artists, it might have been Van Gogh, was driven mad because of the lead in the paint he used. Some artists dip their brush in their mouth to wet it. That may have been what happened to him, and it may have actually killed others.

@Kardamom It was Caravaggio that went mad and then died of lead poisoning from his paints. Van Gogh is also suspected of suffering the same fate, although he exhibited mental illness at a young age.

Well my Mom and sister were / are artists and both were / are depressed. Both attempted suicide in their lives.
I think Van Gogh was depressed and he whacked off his ear.
I think many artists find an outlet for their demons through art.