Who knows why haters do what they do?
Some haters genuinely don't like you or your content, some are just mean people, some are going through stuff and want to project their negative feelings onto you. Sometimes the hate is enduring, where they dislike span everything you do even for months to come, sometimes they will troll your comment section (good for your channel since it adds to your comments and views), and sometimes the hate wanes and they move on or forget about you. Especially if you never take their bait and respond to the hate (hey, nice rhyme!).
I once had a hater who commented and dm-ed some really ugly words to me, calling me awful names. I'm cool with people saying I suck or my content sucks, but derogatory name calling or threats are not tolerated and turn into an instant block and report. So I did this, and they immediately started disliking all of my videos on multiple accounts. This persisted for a few months, until they either forgot about me, realized I wouldn't take the bait, or got through whatever bad thing they were going through in life.
It's important to not care about the hate, and focus on the positives. Take note of criticism if it's constructive, but don't let it mess with you. It's your content not theirs, so the only opinion that matters in the end is your own.