Bandwidth is the largest reason for me as well (followed closely by avoidance of malware). I don't have a monthly cap, but our download speed is pretty low and the advertisements were often the parts of the page that took the most time to download. I actually don't mind advertisements myself, in fact I really like them (definitely a minority opinion) as they've helped me find nice products/services that I later actually purchased/visited (just as an ad is supposed to do), but in the end I can't bother enabling them as the bandwidth and malware risk are too high to make it worth it.
Bandwidth is the largest reason for me as well (followed closely by avoidance of malware). I don't have a monthly cap, but our download speed is pretty low and the advertisements were often the parts of the page that took the most time to download. I actually don't mind advertisements myself, in fact I really like them (definitely a minority opinion) as they've helped me find nice products/services that I later actually purchased/visited (just as an ad is supposed to do), but in the end I can't bother enabling them as the bandwidth and malware risk are too high to make it worth it.