I don't block ads because stealing ad revenue from companies is unethical. These companies have workers who have families that they need to feed. They provide a service for free, so it's the least I can do. I watch every ad in full.

My cousin, however, stopped blocking ads on YouTube when the YouTube warnings showed up. She is scared that at some point Google would ban Gmail accounts for doing it, and she's had hers for 10 years and really relies on it. She also says YouTube videos are really easy to download so anything she really wants from YouTube she tends to have a local copy of.