If I won the lottery, I'd like to believe the first thing I'd spend my money on would not be drugs but to pay bills and to establish a secure and stable financial future. I'd pay bills, and put money aside for months of rent. I might even buy my own place, something modest but still a nice place to live. Then, I'd probably put money aside for emergencies, maybe even invest in an education and a career.
As for drugs, being realistic, I'd buy myself an ounce of weed, followed by a dozen vials of Ketamine. I'd probably splurge an buy a couple of Oxycodone IR's as well, for old times sake. I was never one for stimulants, I've always been a Psyche/Dissociative person. With that said, I might also invest in a Mushroom Grow Kit, and learn to grow a steady supply for myself and others.