"Big gamblers" refers to individuals who regularly take high risks and make large bets in gambling activities. They are willing to wager significant amounts of money in the hope of winning big rewards or profits. Full definition
Keep in mind we're not big gamblers either to get these sort of discounts. (pointsmilesandmore.com)
Another is that the settlers of America were more ambitious, bigger gamblers, more adventurous, and in their travels across the ocean and through the wilderness had seen more of God's natural wonders than the boring and staid royalty and upper class of Europe. (religion.blogs.cnn.com)