I don't know why you wouldn't take the annuity on a sum like that, or any of the jumbo lotteries you guys have.
Aside from the reasons others have listed, if you take it in annual sums, the interest on the pool of money itself is being earned by the government, and not you (plus inflation is working against you). If you were to take that entire lump sum amount (which looks to be about 1/3rd less than the full amount), and invest it in a diversified portfolio, you will have increased that amount by far more than +50% (in real dollars) over 20 years. Even just the inflation effect is going to make that 20th payment worth about half what it would have been worth if you'd gotten it on day one.
And of course, that's ignoring the possibility of the lottery system going bankrupt, state canceling additional payouts, seizing profits, taxes going up dramatically, war, revolution, zombie apocalypse, etc which might cause you to not get that money.