another reason to not always flaunt your wealth is that money and conspicuous consumption brings out hatred and jealousy in others, too. when i started living the good life (nice cars, nice vacations) and met new people, most people at first appeared to be respectfully envious and in admiration of my achievements. as in, "good job! i'm glad for you." but after you get to know them, it becomes clear that some of them have a jealous hatred of you. if you're sensitive about how others perceive you, hide your money.
I drive a 10-year old pickup to work for that very reason. A nice car can cause problems, a nice home not so much because it is not in their faces. The vacations, well I've learned to flat-out lie. My family has rented a villa in Tuscany for 2011. I'm going to try to spend a month or two with them there in the spring. I will tell my co-workers that I'm working at home on the ranch. Something like that. But what I think the OP meant was hiding wealth from *everyone*, that is, living in a modest home and owning modest vehicles. Hiding all the bling from the office isn't the same thing.
In my case, I'm in a technical profession that pays just ok but is very interesting and satisfying. At some point I went to a hedge fund and made some decent money and also made money on a series of home deals at the same time. I returned to my technical job with a small nut and am able to live well and also have interesting work. I may dip back into the financial world at some point in the future if they still like engineers. I think the pendulum has swung back towards preferring true financial professionals with financial degrees instead of technical people but that could change in the future. The people I work with aren't poor but they can become jealous under the right circumstances. About half of them are underwater on their mortgage. I just refuse to discuss money, cars or real-estate at the office. They're good people though and I like working with them.