It's true that it's easy to overlook domestic terrorists, whether it be individuals or groups set out to harm others.

Based on the history of domestic terrorism in the US I'd say it's not AS serious of a threat as al-Qaeda, but that's only based on what's been done by each group.

The total number of deaths caused by domestic terrorism is way more than the death toll from al-Qaeda. Individually though, no the groups are not as dangerous.

Should they still be stopped, yes. I did know they existed but since I never hear about them in the news I haven't focused much attention on them.