He doesn't think imagining winning the lottery is fun, it actually is fun for him. He's actually entertained and is comfortable spending money for a little imaging and escapism.
Lots of illegal drugs are actually fun, too. While they probably shouldn't be illegal, they can easily (much more easily than other things) lead to self-destructive life styles with the user laughing all the way. That's what's wrong with them. Similarly for becoming addicted to gambling, which at least doesn't create a chemical dependency.
Nothing is wrong with that. When I go to Las Vegas, I play craps for the same reason. But I didn't make a massive blog post that implied I could beat craps, get it on page 1 of HN and after 20,000 words and numerous graphs and tables announce to the World that it's ok that I donate some money to Bellagio once a year because it's my money and the waitresses are hot and it's fun. I wouldn't do that because no amount of eloquent prose and statistical evidence is going to change the fact that I just stated the blatantly obvious. That's why everybody gambles.
"But I didn't make a massive blog post that implied I could beat craps ..." He implied nothing of the sort, the headline is a good summary of the post. You are annoyed that the post is not what YOU thought it should have been, learn to read.
What's wrong with that?