Well, hmm. I'm saving up through my next four years to make a sizeable down payment on a USED M-Class or E-Class because I've always wanted one; possibly another diesel variant if MB brings them to the US, but...
Back to his statement, what is a true Benz owner? Is it someone like me, the one who's wanted one his whole life and saved up to get one or a richer person who can afford the service and parts? Would I be wise to do it as well unless I'm working at a six-figure job income?
I don't think there's any such thing as a typical Mercedes owner as their model range covers everything from sporty roadsters to family haulers and vans. They have also made cars long enough that anyone can afford to buy one in some form or another. We all see the perfectly detailed beauties often parked right next to the daily driver "beaters" that are there simply to make the drive home.
My advice to you would be to look for a vehicle that is part of the CPO (Certified Pre-Owned) Starmark program so it will be warranted through the dealer. My '99 was covered until the summer of 2007 and I had no out of pocket repairs until afterward. This will help give you peace of mind at least and despite some shady dealers who have tried to skimp on necessary repairs, I never had a problem getting work done under Starmark at several dealers.
On affordability... yes they are expensive to repair and maintain, but as others have pointed out already, the overall cost of ownership is lower than many much cheaper makes, great news if you plan to keep the car for a long time or forever! Repairs also tend to come up much less frequently as these cars are engineered exceptionally well. That's another point, these are lifetime cars, so always buy the absolute best condition you can afford and you will be rewarded. I received a traffic ticket the other day (bad I know) and the cop didn't believe I had the correct registration because he said my car didn't look like a '99, he thought it was brand new. Of course he apparently can't tell models apart but the point is these cars are made to last and look great doing so as long as you do your part, which is relatively minimal.
Consider this, with a regular car they have a built in life span, Mercedes do not. On older American and most foreign cars you start to have more and more repairs as time goes by and systems and components wear out, with a Mercedes you have less of this because they are built to last. If you choose to keep the MBZ for a long time you also save the cost you typically spending to replace your car. I bought mine on the assumption that I *could* keep it for 20-years and still have less in it than a new American car even considering the original purchase price since it was bought used.
Always try and buy a car with service records if it's older, this proves it was well cared for. Also spend time on the forums for the specific model you're considering to find the common issues within each model/year range. Finally, look online and price some things like brakes, filters, services, motor mounts, all the regular stuff you'd expect to fix over time and decide for yourself if this is within your budget. I tend to believe that most people can find a model they can afford given this formula. Oh yes, don't get in a hurry to buy, there are tons of great cars in every trim level, color combo, engine type, etc., so you will find the car that suits you best with some patience. Good luck with school and with your Mercedes shopping!