I think the strip attracts the first time visitors as it is synonymous with Las Vegas. After a trip or two people learn if they like the Vegas experience and want to come back for vacations on a regular basis. After a few more trips they hone in on exactly what they do and do not like as far as hotels, casinos, games, restaurants, etc. They also begin to realize that saving a few dollars each trip allows them to afford more trips.
The downtown and locals casinos offer a better deal for the regular visitor, especially the locals casinos as they target the Las Vegas resident who wants a good deal on a regular basis rather than having vacation money to spend once a year.
Also, as the regular visitor is realizing what they want out of Vegas, they are also starting to care less about their appearance to others and having a good time themselves. So rather than sitting at a $50 table at Bellagio while waiting on the latest club to open, they are happier at a $5 table off the strip.
It takes a few years to learn these secrets, thus you'll find the older and wiser patron at these places. Myself, I'm north of 50, but started gravitating downtown in my late 30s.
