So you mean that if I find 1000 dollars on the street, they suddenly lose their value and cost nothing, just because I didn't have to work or sell something in order to earn those 1000 dollars? This sounds ridiculous.
Gambling exists for centuries. Money exists for centuries as well. I don't think that they contradict each other, since they both exist for more than 2000 years. We all know the idea of gambling. A bunch of people bet money on the potential outcomes of a game(or an event, in case of sports betting and prediction markets) and the winner takes it all. I don't know about any form or money(fiat or crypto) that lost any value, just because you won them at the casino(or sports betting platform).