Why do some people think something's not worth doing unless it completely solves the problem?

There's a group of people who think that doing something is pointless, if it isn't 100% effective.

Gun control doesn't eliminate gun violence? Pointless.

Vaccines don't completely stop transmission of a virus? Pointless.

Reducing greenhouse gas emissions doesn't stop global warming? Pointless.

Vaccines don't save everyone who takes them? Pointless.

Masks don't completely stop transmission of a virus? Pointless.

Seatbelts don't save every driver's life in a crash? Pointless.

Of course, those same people often think it's worth making millions of people's lives harder is justified if it stops any number from "taking advantage".

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9 mo
In the opposite direction, you have things like: "... some slaves developed highly specialized trades from which they benefitted. This is factual and well documented," it added.

The statement continued, “Some examples include: blacksmiths like Ned Cobb, Henry Blair, Lewis Latimer and John Henry; shoemakers like..." (Florida dept. of Education)
The enslavement of millions of Black people wasn't that bad because dozens learned a trade. This is what they want to teach.
Why do some people think something's not worth doing unless it completely solves the problem?
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