From my observations, I feel that this is a very unusual occurrence, which I''ll elaborate on. Most men that are around 40 and up are well overweight, very out of shape, etc. There are definitely men in this age range that are very in shape, are attractive, etc. but they represent a very small minority, I'm talking less than 5% and even that is being generous.
I recently turned 31, am well over 6' tall and if I go to any standard gym I'll easily be in the top 5% of men there physically. Most of the women that I have been on dates with in the past few years ranged from 19-40+, though most were around 22-early 30s.
I feel there is a huge difference dating/going for women in their mid-late twenties in comparison to those in their early 20s. Women in their early 20s are still barely out of high school, are often still in college and just starting to get into hitting up nightlife scenes, partying, etc. I feel women in this age range are still more or less going to go for the guy who is fun and reckless, as that is what they are in this time period.
However, I feel once women starting getting into their mid 20s they start moving on from this stage and once they start creeping towards 30 their priorities start changing and they are looking to potentially settle down. I feel this is the age range that older men can work with but you need to be able to attract them in the first place. What people on here seem to forget is that you are also competing with men who are around their age and up, so potentially a man that is close to a decade younger. You really need to have a lot you are bringing to the table and I have the inclination that if a woman is going for a man that much older it mostly will be due to financial/career status.
I feel people see too much of celebrities like Leonardo DiCaprio dating women 20 years his journey and think that is a representation of the real world.