Capital gains taxes. When the "fair market value" of the company increases away from your strike price, when you exercise your options you have to pay tax on the difference between your strike price and the fair market value. And it will be a short term capital gain so it isn't cheap. If those .20 options of your have a fair market value of 5.00 now, you will owe tax on 4.80 of capital gains. 4.80 * 100,000 is 480,000.00 and a tax rate of about 40% on that means you will owe $192,000.00 in taxes to exercises $20,000.00 in options. So you will need around $210,000.00 to get out.
And even after that you're holding a non-liquid asset which could be diluted to nothing or the company could simply fail and you can't dump the stock.