Science would agree that most people do not need to worry about moderate daily caffeine consumption. 400mg/day (for men) and 300mg/day (for women) is often listed as a reasonable, safe upper limit. 3-5 cups of coffee is also often found to be safe, healthy even, in research, with 6 cups seeming to be the upper limit at times. 300-400mg/day would probably be conservatively advisable, with up to 500mg still likely being fine, maybe even 600mg, but that’s pushing it. 700-800mg can be excessive though, especially for daily/regular use, I agree.
These people were talking about having caffeine daily period, or even just using caffeine pills regularly.