"Negative-emissions" carbon-capture technologies have essentially intractable problems scaling up, including basic thermodynamics; that isn't even talking about the massive resource inputs to build a system capable of meaningfully reducing CO2. It's a lot easier to to not emit as much in the first place.

Even barring these severe problems, the precautionary principle is the right thing to apply here. If "negative emission" tech has even a 90% chance of working, we still should focus on reducing emissions, because that tail risk is bad.

It's like why people have fire insurance even though most people's houses never catch on fire.