I like to think I'm a good wolf @dragosroua and like you, I upvote most comments.
I also upvote posts even though my votes aren't worth much. Mainly because I like to do unto others as I'd like to be done unto myself and even small votes add something.
I'm very grateful for all the upvotes you give me, and for those from @raluca, and for the time you take to explain stuff I don't understand. Thank you very much for that! 😍
It's not about good vs. evil but smart vs. stupid. Not upvoting comments in your comment section is simply stupid if you're after rewards at all. The rewards your upvotes direct somebody else's way do not even come from you but the common reward pool. The only cost to you is a small temporary loss of your voting power. Upvoting someone will often trigger a desire to upvote you in them.