They have almost no impulse control because everything came easily to them up until that point in their life. Since they never experienced negative consequences for any of their actions, they never learned to think and plan ahead, or consider the possible dangers of an action beforehand.
Another aspect is that they have little to no capacity for introspection or self-awareness, for the same reasons as listed above, alongside the fact that they tend to very rarely be alone with their thoughts so they never spend time thinking about things.
Some incels will end up with the opposite problem, due to experiencing extreme difficulties and stress, as well as chronic loneliness, over the course of their life, they may end up living inside their own head and overthinking things. Often times this can paralyze them into inaction, either because they spend too much time analyzing situations and missing opportunities, or because they desperately want to avoid enduring more suffering so they become overly avoidant of sources of stress, and sometimes a combination of both.
