Income wise we're in the middle of middle class. Our home is very modest and 50 years old. We've refinanced several times for better interests rates but never took out cash or pushed the pay off date out further. Our newest car is 9 years old, oldest is 16 and the coach is 8. We don't get new cell phones every time a new model comes out. Our closets have cloths and shoes that are not wear once and hang up. Our primary TV is less than 50" and we don't subscribe to every premium cable channel possible. Our debt is under control and we're on tract to a comfortable retirement when we're ready. Income is a factor but how you use it is has a much greater effect.
Is owning and traveling in a RV cheep? No but for us ownership costs are much less than plane fare, hotel, rental car and such that others might do for as many days out a year as we enjoy in our coach.
Personal wealth is all in the mind and if you're constantly trying to out do the neighbor or if winning the state lottery is your retirement plan, well good luck.