What do I do with my Cash? As long as it is in a safe account, Nothing. But it gives me incredible leverage flexibility when I need to get things done. I have stated in the past I will use my wealth as a shield against those that would do harm. And like you I live modestly.
I've been there and done that and now I'm going to enjoy my life, because over the years I've earned enough tangible assets to make this happen. I plan to buy my last house in CASH... I then will buy my 1962-63 Lincoln with the suicide doors with cash as well. Both are Tangible assets and given time both will go up in value as well.
Work hard when you are young.... Work easy when you are old. I'm working easy now
IMHO you have to have a certain amount of cash to do things. As stated before I'm 65% income investments, 30% Cash, 5% Stocks. With Cash I can immediately buy more income investments or play the stock market or if there is an emergency I have it NOW. If I was younger it would have been 50% income investments 20 to 25% cash and 20 to 25% stocks. Age does play a critical point in investing.
When you are young you have the flexibility of youth. That is why I am HYPER Critical of people wasting their time and money away on things they DO NOT NEED BECAUSE THEY WANT IT NOW...
Next, I have "Oh Shit" Money I keep a small percentage on hand to deal with those emergencies that require cash. Yea I got great credit and that is used only as backup as I do not like credit card debt or any financial debt that does not benefit me. A good example of a good debt is taking the interest off of your mortgage for tax purposes.
Now the Stocks. I see no problem people playing this game. And I suggest you have a very diverse portfolio when you are dealing with stocks. If you are young (under 55 years of age) then go for it. You can be a bit riskier if you have money to play the stocks in your 30's to 40's, so if you take a loss you can recoup it later via time.
Just don't get fucking greedy. I've seen that happen too many times when they invest on the "sure" thing.
Right now at my age I have to be more conservative in what I do. 13 years ago I took a chance and got in and purchased some investment property and sweat equality it like I have done the rest. And it paid off handsomely.
My stocks ATM are Energy.