Illinois has had difficulty recently paying lottery winnings to citizens. In 2015, 3900 winning tickets had delayed payouts [0]. Risk should always be factored into financial decisions, and risk of a lottery institution going insolvent is non-zero.
They did pay, but yes, nothing is completely risk-free. The risk of a lottery winner losing their lump sum to mismanagement, fraud, etc. is still a lot higher than the risk of a state going belly-up, although maybe Illinois will be the one to change that.
[0] http://money.cnn.com/2017/06/27/news/illinois-lottery-state-...