If you create a field in SQL to calculate the number of visits each user has made you can then simply add that field to a histogram to get the number of users who have made n visits. This is a workaround to the Quicksight requirement of including the field used in your calculation in the visual which is not possible in the histogram in this use case.
Another option is to do the above but using a bar chart and the User_ID field which will allow you to see the specific value in the x-axis instead of the range of values you will have in the x-axis if you use a histogram.