Perhaps the most important thing I've learned from reading MMM is that the paradigm of budgeting based on percentage is a bad idea. It seems that people love a justification for buying shit they don't need and pointing to a percentage of spending that is "acceptable" seems to reinforce that idea. I could almost accept the idea of a percentage budget if those numbers had more realistic values for saving/retirement but then you get the complainypants brigade proclaiming it is impossible (their comments typed on a new iPad bought on credit for extra impact).
I live very comfortably right now, arguably more than I should. But that being said I am very conscious to avoid lifestyle creep and constantly seek optimization. My lifestyle is not totally frugal, especially compared to many people here. But my idea is that as long as I follow a mentality of optimization and avoiding luxuries that only increase comfort and appearances (especially those prone to hedonic adaptation) one can be succesful. This is compared to the line of thinking of "I can't wait til I make X (salary) so I can buy Y (something I don't need)". I feel like this is where it all goes wrong for many people. Rather than living a reasonable lifestyle and taking financial security they will increase spending to match any increase in income. While this gives them more "visible wealth", ie fancy lifestyle, fancy car and big house, it still leaves them in the same precarious position that people with low income face. But in this case they do it to themselves and still have the audacity to blame systemic problems.
It almost seems like there are three major groups of people in how this is managed.
1) People who realize that many goods and comforts do not enrich or improve quality of life significantly.
2) People who want these goods and comforts but are willing to save and budget to manage them financially while still securing a sound future.
3) People who want these goods and comforts right now because they believe they are entitled to them. They will purchase these on credit or at least on the edge of financial stability and will blame others when the situation goes south.
Personally I fall somewhere between 1 and 2. I still indulge but try to be conscious to invest in those hobbies and interests that stimulate my thinking and skills. Balancing the interest in these hobbies while also being aware that buying better things constantly only increases your standards of "normal" over time.
