How long does it take you to draw something like that?

Well, you can read this post about witness:https://steemit.com/steemit/@cryptohazard/why-i-want-to-improve-steem-security-and-become-a-witness. Long story short, we are the guardians of steem. Our role is basically to take the transactions, like for instance this comment, and put them in blocks to build the blockchain (I don't know how familiar you are with bitcoin etc.). Depending on how much Steem power your voters have, you get a higher ranking position, hence make more blocks and get more steem (one per block). People don't vote that much because they are unaware they are supposed to do so.