[Cronos]

The winner will now have to decide between the 29-year, 30-payment annuity, and the cash option worth $177.3 million

What's the reason for this?

[Hillarys Gate Cult]

Good question. If a multi million dollar winner takes the annuity, they only get about $ 100,000 dollars up front and then the yearly installments. One can invest the lump sum better, the lottery may not be around forever, plus the person knows they may not live 30 years ( or be in any condition to enjoy it by then ). No idea why the lottery still keeps half but if it wasn't the government running things, they would be sued for false advertising and lose the case.

IIRC, several winners have sued over the years to get the whole amount of the jackpot and have lost every time in various courts.

The half of the jackpot started with the earliest lotteries I have heard of and every new lottery since then has gone the annuity or lump sum amount. It's a cash cow for the government, just on the jackpot part.