The purpose of this study was to examine how dependent the online gambling industry is on people who gamble heavily. Seven leading gambling operators in Great Britain provided the researchers with data for 139,152 people who gambled at least once between June 2018 and June 2019. The findings showed that people who were in the top 20% in terms of amount of loss, generated 89.2% of the net revenue for the gambling operators. The top 10% of people generated 79% of operator revenue, and the top 1% of people generated 37%. But the bottom 50% of people generated only 0.5% of the net revenue. The revenues generated by sports betting and bingo were not as dependent on a small number of people with high spending. Even then, a few people accounted for a significant proportion of the net revenue. The researchers discussed how restrictions of account deposits or losses might pose a risk to gambling operators because a minority of people contribute significantly to their net revenue.