True, it can be scary. But perfect love casts out fear. Luke 6:43, like many verses, points to a reality. Sin proceeds from an evil heart and defiles us. We know this as "the flesh". The fleh will never be any different than it is, because an evil tree can only produce evil fruit. Thankfully, by the grace of God, we are not under law, but under grace as concerns the flesh.
But there is another reality for those who are born of God. Jesus lives in us, and we have been made one with Him in the new man. He's in us, and we're in Him. He is the good tree in us, and from Him flow all the good fruits. So, we can walk in lock step with the Spirit and see the good fruit in our lives because walking in the Spirit produces good fruit and supresses the bad fruit.
So, we should not only recognize the the badness of the tree that produces sin in us, but we also should also recognize the goodness of the tree that produces righteousness in us.