You will get downvoted in any disagreement, that's not exclusive to reddit or Lemmy, that happens in any social media with downvotes.

The purpose of downvotes is to show what the general people in that common section think about your comment. You shouldn't give any hoot about it other than the info it provides.

Obviously, if you are talking in controversal topics or ones with conflicting sides, you are gonna see alot of downvotes. Its just people expressing their opinion.

Echo chambers are just a natural part of communities. People often come to feel validated so they stick to ones with the same thoughts as them. I don't recommend trying to argue/discuss with people who only want to "win" cuz there's nothing to gain.

Talk with those who argue because they want to learn or understand something better. (or perhaps help you learn something new)