Earning $1,000 - $5,000 a month from gambling is very difficult and takes a lot of luck.
He is talking about that amount but monthly. But by talking about gambling in general, without distinguishing between skill games and casino games he shows that he has no idea. And even if someone is earning those amounts in skill games it would be very rare for him to be participating regularly in the forum, where participating in signature campaigns is not going to earn more than a few hundred.
There's nothing you can do in gambling that you can earn constantly from, everything was designed randomly, so even if you were to gamble on skilled based games like football and other sports games making such an amount monthly is still not guaranteed. I thought I found a way out of the matrix with gambling few years ago with short football games on 1x bet, there were paying off at first, I remember rolling over for two weeks playing those games without losing any bet but after turning 5000 naira to 100000 naira I lost it all in the 3rd week.