I'm often told that these groups aren't dangerous because they're small in number and marginal. We often estimate that the far right in Canada amounts to less than 1% of the population. Political parties that have a far-right ideology don't get many votes. The parties will get less than 1% of the vote. They won't succeed in getting members elected to Parliament, for example. Within the population, these groups are extremely marginal.
However, just because they're marginal doesn't mean that they aren't dangerous. For a terrorist attack to occur, all it takes is one person fuelled by extremist ideologies. We saw this in the attack on the Great Mosque of Quebec City. The small groups are dangerous given that it takes only a few individuals for these types of acts to occur. Moreover, an individual becomes dangerous when they're desperate, meaning when they see that their political option has no hope of being democratically recognized or of succeeding. At that point, they may think that violence is the only way to further their cause.