I legitimately had no idea just how low my income was until I had a conversation very much like the one in this comic. Even the office job with a major international corporation that I had prior to becoming a full-time cartoonist paid a fraction of what that friend made. That job was my entire basis for what constituted a "decent income", but that conversation disabused me of that notion.
Since then, I've readjusted a lot of my goal posts when it comes to freelancing. I've increased my rates to account for the changing markets, and I make a real effort not to short-sell my work. Times and prices change, and freelancers in particular have to change with them. So don't be afraid to ask your colleagues and close friends what they make. You might be surprised.
Rock on, guys, and never stop drawing.