I've recently been thinking about the concept of
signaling. Signaling is the idea of communicating something about yourself using something else that isn't necessarily related. For example, a college degree is a proxy for being a good worker, and peacock plumage is a proxy for genetic fitness.
From this perspective, fancy cars and big houses are plumage, that is, signals of success. Obviously, you can be successful without them, but some people want successful friends, and they often can't tell whether you're successful without the accepted proxies, so if you don't have them, they will treat you differently, or they'll be confused, and it will be an uphill battle to gain acceptance. Think of how a self-taught person would be treated if they applied for the average job requiring a bachelors degree, even if they were a better worker.
Given this perspective, there are a few different ways to deal with it.
For one, you can still acquire the signals, just much cheaper than everyone else. This would be fixing up a classic car, or transferring from community college to a name-brand college after two years, or building and fixing up your own house, or riding your bike all the time because you're cross-training for a marathon (which is an accepted signal), or getting cheap vacations by trading houses with another family, etc. This offends fewer people, but you still have to deal with problems of being surrounded by rampant consumerism and feeling out of place.
Another way to deal with it is to escape the need for signals, or be part of a community that uses signals that are acceptable to you, or one that uses the same signals, just on a smaller scale. Just like a self-taught person can get around the degree-less applicant issue by producing a valuable portfolio and becoming self-employed, a frugal person can find a frugal community and hang out with grad students, artists, tradesmen, or just people in the "lower middle class."
I know that this says a lot of what's already been said, but there is one concept of signaling theory that might add an interesting perspective, and that is
countersignaling. This is the idea that people with middling qualities expend more energy to prove themselves than people with high qualities. As a familiar example, if someone hangs out with less wealthy people, they don't feel like they need to show their wealth, but, if someone is like most middle class Americans, they spend tons of money keeping up with the Joneses. A financially independent person feels less of a need to prove worthiness. (Granted, there's a question of causation here.) The application is that someone might be able to bluff their way into acceptance by not buying as big a house or as expensive a car, perhaps by adopting a Steve-Jobs-like minimalism. I'm not sure what it would take to make this work.
Food for thought.