I just turned 30...$95k between 401k, Roth and cash savings. I just started making decent money in 2008 ($100k base) but also started an MBA degree at a top 5 program, which eats about 25k a year (evening program).
Sadly I've calculated my entire net outflows...$102k each year since 20008. That does include school and ALL expenses. Pretty crazy that I've still managed to save what I have. I actually saved more per year when I made less (about $65k), but I anticipate my base income bumping to +$150k per year once I graduate in June so I'm not too concerned. Moral of the story, you don't need much if your expenses are low. The more you make the more you tend to consume. As you get older, you anticipate lifetime earnings, not just annual, so you consume accordingly. This is a well researched fact of human behavior.
I am a banker and have studied money extensively. My advice: spend it now and don't worry about borrowing if you can borrow below 8%: fiat paper will be worth shit in about 10 yrs. Anything you borrow now will be paid back on a heavily depreciated basis. Just make sure to get fixed rate loans now (which are at historic lows) so that you won't get f***ed in the ass by inflation, which is gonna spike (the Fed has said it WANTS to increase inflation b/c its below its randomly selected target).
Flagpole: In general, your very basic principals of living below your means is an acceptable philosophy. However, your investment advice is shit. I simply offer this explanation. I was talking to a Nobel Prize winning Econ professor (we have many). I said, do you really believe in the principals of an efficient market. He said, "of course". I asked, and isn't it true that most of the math in economics is based on the principals of physics? Again he agreed, of course it is. So I asked, would the laws of physics apply whether man is on earth or admonished from its face? For a third time, he agreed. And I said, well is that true about economics. By gut reaction, he replied yes, but then paused. So I said, before you say yes, think, would our economics work in Soviet Russia. He said, well of course not, they were not a free market economy. And I replied, exactly. The markets are driven by humans, who exhibit animal like behavior. In other words, they adapt. Unfortunately, the markets, by human behavior, have been proven inefficient because our behaviors have changed. The math behind economics is flawed because it does not anticipate changes in behavior as it actually occurs. Think of it like this: Economic models anticipate change within a define set of rules. The problem: the rules have been broken and the game changed. It is the vampire of Wall Street who will insist at every opportunity to ignore the burning house and to keep buying furniture to put back in the burning house. In other words, you'll simply be throwing good money after bad. To all the dipshits who keep insisting that commodities are the way to go, I laugh. The best way to go is consumption. Calculate a cost of capital based on your happiness derived from the beta of risk that the government will only f*** you harder in the future (trust me, that beta risk is well over 1.0)
Aside from consumption and your happiness, the best investment in the next 2-3 decades will be any investment that lowers your tax liability. In much the same way that you could easily calculate the housing bubble by looking at the ratio of housing price to wages or wage growth, you can look at the ratio of national debt/expenditures to GDP. It will be impossible for the government to maintain itself w/o raising taxes. So anything that you can invest in that will lower this liability will buy you an immediate 35%+ return (or higher since pretty much everyone with a brain anticipates future increases).
Again, I am a banker (for now)...I see how the rules are made, b/c, well, I have a hand in making them. The house wins a majority of the time, and you the consumer/middle class are not the house.