Not everyone here is into "extreme" frugality - there are plenty of us who balance living well:) whatever that may mean to each one of us with our values and our own ideas of frugality. MMM is a lifestyle, not a cult:) and it does not have to mean "extreme" frugality either.
I don't particularly care for anything that is extreme, but there is a large segment here on MMM, that came from a blog/site called ERE which is rather hard core.
Extreme frugality may serve it's purpose on a temporary basis for people who are just beginning to see the light and are revamping their financial life or because it is the only way to make something happen, because lord knows there is no chance of the current income going up in the near future for whatever reason...
Many live extreme frugality to make up for lost time, lost opportunities, tough circumstances, ill health/divorce or stuffing the mouth of the debt monster - so they can breathe again and start their (financial) lives over from scratch.
High student debt and a low or average paying job will do that to you.
None of that applies to you. You did well for yourself. Your numbers show you live on 10% of your income - nothing wrong with that in my world.
However, I will point out two things - you must be considering your values or your monthly expenditures in a new light and at least vaguely re-evaluating them or you wouldn't be here poking about, looking for answers from a different perspective.
Also, while I hate to admit it, Steve made an (almost:) valid point about your monthly living expenses, if you can live comfortably on 30K, then 40 or 60K a month is excessive. Of course, I cannot quite agree with that point, even if it sounds sensible and righteous and will save our planet/species from extinction - I lean toward the idea that growing up poor does entitle you to enjoy the fruits of your labors (or rather intellect:), you do have some catching up to do in the form of toys and fun.
You are already sharing the wealth (which I think everyone should do - no matter how little or how much one has) giving to good causes and your family, perhaps doing your bit to make this a better world, so I don't see the point in criticizing your current level of spending.
However, maybe it is simply time for you to re-evaluate your personal values and outlook and consider a few changes going forward. Maybe you have reached a turning point in your life?
This may not be a popular view on MMM, but I think living on 10% of your income at $40K is a good thing. Perhaps at some point in the future however, that 10% might become so outrageous (as your income goes up), that it will indeed become a life of such indefensible excess - that it is hard to applaud and justify, when your tip at a high roller restaurant is higher than a week's groceries for a single mom and child ... just saying, that it is a good idea to draw the line somewhere.
Perhaps it is simply an exercise in self discipline or refusing to give in to greed and excess. I think in your shoes I'd play a while too, but eventually I'd know it is enough and it would be time to shift perspective and move on.
I think ordinary people, like in the book the Millionaire next door, have an easier time to find and maintain a balance than someone who experienced poverty as a child. It skews your perception of money for the rest of your life.
The trick is to find the right balance, to live according to your own values and decide on your own lifestyle - something which bears reviewing from time to time as your life and perspectives change - which they will as you grow and change yourself.
Welcome to MMM - I hope you find the insights you are looking for:) Since your situation is rather unique and enviable it may not be easy for you to see clearly what your next, best move should be to live a good life - not just financially. You are smart - you'll figure it out - challenge yourself and voila, you've joined the club:)