The promotions they do will also certainly be able to attract more people who will play on their site. It is hoped that with the right promotion, the profits of a site can increase.
Not only does it attract more people but it also encourages their existing players to continue playing. Even if it's only a classic wagering competition there's still a significant increase in wagering activity.
You are right. Therefore, these gambling sites continue to focus on promotions to attract more people, especially if they can provide promotions that attract people and big players. If they can get a lot of big players, that means the gambling site's profits can also be more than before. And providing lots of gambling games will make gambling players feel more comfortable playing on their site.