Breaking 90 in golf is considered a significant milestone for amateur golfers, as it represents a level of proficiency and consistency that is required to play at a high level. However, the percentage of golfers who are able to achieve this feat varies widely depending on a number of factors, including age, skill level, and amount of practice.

According to various surveys and studies, the percentage of golfers who break 90 on a regular basis (i.e., in more than half of their rounds) is estimated to be between 10% and 25%. This means that the majority of golfers, regardless of age or experience, struggle to consistently score in the 80s or below.
There are a number of factors that contribute to the difficulty of breaking 90 in golf. These include the length and difficulty of the course, the quality of the golfer’s swing and ball-striking ability, and the golfer’s mental approach to the game. Additionally, factors such as weather conditions, course conditions, and equipment can also play a role in a golfer’s ability to score well.
Age is another factor that can influence a golfer’s likelihood of breaking 90. According to one study conducted by the National Golf Foundation, golfers over the age of 60 are much less likely to break 90 than younger golfers. This is due in part to the fact that older golfers tend to experience a decline in physical ability and stamina, which can make it more difficult to maintain consistency throughout a round.
In terms of skill level, golfers who have a handicap of 10 or lower are much more likely to break 90 than golfers with higher handicaps. According to the same study conducted by the National Golf Foundation, golfers with a handicap of 10 or lower are more than twice as likely to break 90 than golfers with a handicap of 20 or higher.
Finally, practice and training are also critical factors in a golfer’s ability to break 90. Golfers who practice regularly and receive instruction from a qualified coach are much more likely to improve their swing mechanics, ball-striking ability, and mental game, all of which can help them break 90 on a consistent basis.
In conclusion, while there is no definitive answer to the question of what percentage of golfers actually break 90, it is clear that breaking 90 represents a significant accomplishment for amateur golfers. While the majority of golfers struggle to achieve this milestone, with the right combination of skill, practice, and mental approach, it is possible for golfers of all ages and ability levels to break 90 and take their game to the next level.