Using a simple t-test calculation and assuming normal distribution and an equal split in both groups, the sample size per group needs to be 20 million to be in

Using a simple t-test calculation and assuming normal distribution and an equal split in both groups, the sample size per group needs to be 20 million to be in the 90% confidence interval. It's not even yet in the 95% interval at that point. You reach the "scientific default" 95% confidence at 40million per group (that's 80million total). At a sample size of 20million that's 182.800 cases in the non-alcoholic group and 183.600 in the alcoholic once a day group. At that scale I wouldn't trust my data enough to believe the reporting of once-a-day and not-at-all is actually accurate and other completly unrelated unaccounted effects do not outweigh my testesd criteria. If I haven't done any major errors calculating this (which might be, because it's back of the napkin math with a t-test calculator or my assumptions are wrong), I doubt the sample size and accuracy of the measure is high enough to make a statistical significant claim about these groups. Even if it actually is a somewhat accurate result, it means having one drink per day increases health issues by as little as 0.5%. The risk of addicition and starting to drink much more probably heavily outweighs that. Regarding OPs statement, I think it's fair to assume what is usually meant is "that has to be statistically insignificant for any sample size this sutdy probably had".