Never compare yourself to other people. Each one is unique and has an unique life-story. You don't know what their needs, financial conditions and personality are, as they may be completely different from yours, so you will be comparing yourself to a completely different scenario which you wouldn't even know how you would react if you were on their shoes.

Only compare you to yourself taking into consideration your personal potentials in order to achieve your goals. Regards gambling, you have to analyze your financial conditions. Do you have money you can afford to lose through gambling? How much? In positive case, set a fixed sum and don't cross the line, even if the friend by your side is spending a much superior amount of money.