The odds of buying a winning ticket are low
On a typical lottery scratch ticket game, the odds of winning a prize are about 1 in 4, which means for every four scratch tickets you buy only one will be a winner. Most of the winning tickets are for small amounts, so if you buy four tickets and get one winner, it will rarely win enough to pay for all four tickets, thus you will lose money. For instance, Washington State's Loteria scratch ticket game (a $2 game) there are 3,485,100 tickets printed and there are 963,359 winning tickets. However, 644,781 of those winning tickets only pay $2 or $3, so the odds of winning a $5 winner or up are only 1 in 11. The odds of winning the top prize of $20,000 (four winners) are 871,275 to 1. Not very good odds. The odds improve to 1 in 3 for the most expensive Washington State lottery scratch game, "$80 Million Payout" (a $30 per ticket game), but in that game the odds of winning a prize of $100 or up are only 1 in 19, and the odds of winning the top $2,000,000 prize (3 prizes total) are over a million to one.

The payout rates are low
Generally, lottery scratch ticket games are stingy in how much they pay out vs. how much they take in. For instance, Washington State's Loteria $2 scratch ticket game takes in $6,970,200 (assuming all the tickets are sold), and pays out a total of $4,532,120. That is a payout rate of only 65%, which means for each dollar taken in, only 65 cents is returned in prizes. The payout rates do get slightly better with higher priced lottery scratch ticket games. Washington State's most expensive scratch ticket game, the "$80 Million Payout" (at $30 per ticket), takes in a whopping $109,352,250, and pays out a total of $84,684,725 in prizes, for a payout rate of 77%. That's better, but still is rather low. By comparison, the average casino slot machines have payout rates of about 90%.

Of course, it is the lure of winning the big prizes on these games that brings in the players, even though the odds are so bad. After all, even if the odds of winning a million dollar prize are over a million to one, what are the odds you will gain a million dollars without playing the games? Probably zero for most folk. Plus, the game tickets are convenient to buy (being sold in most grocery stores these days), and some of the games are fun to play and can provide some mild entertainment value, so why not play once in a while? I personally like to purchase a lottery scratch ticket once in a while (maybe one ticket a month) but the most I've ever won was $20 on a $2 ticket, and I usually say to myself, "Bah, lottery scratch ticket games SUCK!" Over all, if you are looking to actually WIN money gambling, you have a much better chance playing slot machines at the local casino.