For a self employed man of 48, with not one but two crises under your belt, you are doing pretty damned well.
I do wonder how many people who proffer free advice operate their own businesses and are debt free.
Diversification is great, and asset building is wonderful. However, it is statistical fact that most created asset wealth happens just a bit later in life for people who operate their own businesses (the 50's are the golden years for this).
You are right to be thinking about these issues, right to ask these questions, and right to start investigating.
New York is not middle America. Anyone who lives in New York and is debt free (or has a positive balance sheet) is the exception and not the rule.
My work is professional advisory services to "unique" people. I cannot tell you how many times I have been called in on the cleanup crew when men (even titans) who know how to do their business well get involved in something else motivated by asset creation, wealth management, fear, etc.
The scale is different but the circumstances are always the same.
By the way, if you are a debt-laden billionaire or a debt-laden hairdresser there really isn't any difference. (read the tragic Ralph O. Esmarian story in today's NYTimes http://www.nytimes.com/2008/04/20/fashion/20jewels.html)
The best place for a business owners capital (especially in a small business) is in that business. Grow the business and you grow your assets.
That does not imply being reckless (though risk is part of entrepreneurialism). Neither does it imply avoiding a minimal safety net (i.e. health insurance + one year of savings).
It is not irresponsible to live well, travel, and have fun. I repeat, if you are debt free, don't use credit cards, etc. there is absolutely no reason to levy this judgement upon yourself.
If you want to diversify, find a way to do it that you will enjoy. Some people enjoy squirreling away money in financial vehicles and others do not. Using your knowledge and acquiring assets can be extremely enjoyable.
Beware of people who sell fear. Fear is the world's easiest and most salable product. Almost anyone will buy it. Furthermore, the fear cycle feeds upon itself. Maybe the best single thing you could do for yourself is to unplug your television set and turn off the radio.
Analytical thinking, truly analytical thinking, about the global financial situation requires more background knowledge and more access to information than you are going to be able to obtain. What is happening in the world is not what it seems upon first examination and it is not what is being sold in the media.
Since a "little knowledge is (indeed) a dangerous thing" it is better to stick to what you know. It is obvious, from what you have written, that your business is what you know.
Specifically regarding mortgage backed securities, student loans, credit card companies, hedge funds, the war, and everything else, it is all well beyond your control. You can exert no control over these economic factors and, I repeat, they aren't what they appear to be anyway.
The only thing that we can control is that we think clearly, enjoy living without obsessive spending (and it hardly sounds like you indulge), and avoid debt. (personally I have no debt, no credit cards, no mortgages, no car loans, etc. I don't even take out short-term debts like rental contracts without prepaying the entire contract in advance. This is extreme but it has saved my ass more than once.) Work on slowly building assets (those should be things that are fun for you to acquire and fun for you to have).
When it comes to assets, I firmly believe that assets are something that you should buy and not something that anyone should sell to you. This is a subtle but profound difference.
As for working triple hard, I would end by saying it is worth working triple smart. You are correct in understanding that the key to your future is in your work. Your work, your business is your number-one asset and whatever you do to enhance it, grow it, and diversify it will pay dividends in exponents of any other investment you could possibly make.
Good luck to you,