Immediately after I started making money in virtual worlds I started planning what to do with that money. My InWorld currency amount was getting larger and unallocated resources always irk me, which is one reason I love RTS games. So there will come a time when you begin reaping your first set of profits from virtual worlds, for me this was all coming from SecondLife.com at the time, for you who knows, could be any virtual world that is out there. The point is you have to figure out what to do with your profits. You could invest them all back into your virtual world business, keep doing what your doing, and keep re-investing all of your profit and just hope things continue doing well. The reason you should not reinvest 100% of your profits is the AvRich Rule #1, Nothing lasts Forever.
Virtual worlds have a fast pace economy. This economy is driven by the users, dependent on the world developer’s regulations/rules, and things can change in the blink of a pixel. What if you were running a casino in SecondLife? It was getting bigger, more popular, and more Lindens (SLs virtual currency) were rolling in. You decide to take all of your profit and you think big. You purchase islands for new themed casinos, and you pay builders/scripters to start construction on your SecondLife casino empire. Then, in the blink of a pixel, SL bans casinos and gives you 24 hours to shut yours down. If they hadn’t you would have been making 5x your previous profits, but you got greedy and forgot the rules of the game can change just like that.
So if you cannot have full control over your virtual world empire what are you to do? Rules and regulations can put you out of business and you have no recourse. This is why you need to know that Nothing lasts forever, and in virtual worlds they last even less.
This is why when I first started profiting in SecondLife, I took a step back and pulled money out of the system. I cashed out most of my Lindens and put my USD into my RL bank account. I realized how much potential there was in Second Life but respected the odds are not in my favor. I decided profiting in SecondLife was risky so I needed to work fast, profit, cash out, and repeat. This is my own little personal formula;
Profit in SecondLife
10% Left in Lindens
90% Taken out used for: Payroll, Equipment, LL fees, and the rest pure profit.
I dont plan on working all of my life (if you consider playing in virtual worlds a few hours a day work) so when I had my healthy virtual world profits I made a decision. I would not spend it foolishly, I would instead invest it in the real-world. Using what I learned in Second Life about renting out property, I took my Second Life profits and bought real life real estate, more specifically condos/townhouses. I bought them with the money I made off of virtual real estate, and now own my personal little realty company. This gets me real world assets, a steady cashflow from rents, and if anything bad happens to the virtual worlds I’d be just fine. 
That’s one of the routes I took, and of course there are many many more you can take. You could simply use your virtual world profits to pay off your home, buy a new car, invest in the stock market, make a rainy day fund, or just place it all in your bank where it will be nice and safe. Its great to profit BIG in virtual worlds, but not holding on to your profits is just as bad as never making the virtual dough in the first place! This is one reason if I’ve ever talked to you InWorld on any of my accounts, and you ask me how much money I make I would have said, “It doesn’t matter how much money you make, it matters how much money you keep.”
How likely is it that the way you are profiting will be at the same level in a year? Will the niche you are in be saturated in a year? Will there be room to make profit? Can you keep up with the constant change? You need to hit the virtual streets hard and profit as much as you can! Just dont lose sight of your end goal of cashing out because nothing lasts forever.
So how do you currently approach your profit in virtual worlds? Letting it stay in the virtual world? Reinvesting? Cashing out?