Unclaimed prizes are kept by the lottery jurisdiction. If a Grand Prize goes unclaimed, the money must be returned to all lotteries in proportion to their sales for the draw run. The lotteries then distribute the money, based on their own jurisdiction's laws, to other lottery games or to their jurisdiction's general fund, or otherwise as required by law.
The Mega Millions jackpot was most recently won in the draw on 24 July 2018 when after 22 rollovers, a single ticket purchased in San Jose, California won a jackpot worth $543 million ($320.5 million cash), the 3rd largest Mega Millions jackpot ever! Roland Reyes claimed this incredible jackpot prize on behalf of a group of 11 co-workers from the financial industry. Each of the winners contributed just $2 to the joint ticket, which was purchased with a Quick Pick random number selection. The members of the office pool said they planned to continue working despite the enormous prize money they won.
The advantages to group game tickets is that is a good way to maximize your exposure (you have a little bit of a lot of tickets) without spending fortunes of multiple tickets. Due to the US Powerball having a minimum jackpot of $40m, group game tickets are always an attractive option as even with only a 2.5% share of the syndicate, you will still win $1m! As the jackpots grow, the Syndicate option becomes more and more appealing. The mantra of the group game player is “it’s better to have a little bit of something than a big bit of nothing.”