I think a Player in the Top 100 can get enough money just by playing. But that's round about 200 Elo above Gormallys rating. Many are in between.
When you visit some one day rapid tournament in germany with 200 € for the first place, you could find some IM and GM fighting for that money. At least one of them looks like he really needs that money to get something to eat in the next week.
So one should become a world class player or some money by giving lessons, writing books and columns or do any "normal" job.
In 2016 Daniel Gormally published Insanity, Passion and Addiction - A Year Inside the Chess World.
The book is great, but rather depressive, as it shows how hard GMs have to work to get very few money. The problem is that he doesn't like to coach or to give lessons, so he has to make money playing tournaments. There is not much money around, and he have to win if you want to pay your bills. I think a lot of young players with aspirations to get GMs would think twice if this is really a good idea after reading Gormally's book.