Usually what makes gamblers stake their properties on gambling are as results of not being able to provide funds to stake on or before undergoing on the risks. It's solemnly deep to their instincts that the game is an assured winning game and by then, they're intentionally ignorant that there's no assured games in gambling even while they've formally been aware of the winning and loosing percentages of the gamble and then gets regret when the bet gets lost.
You are right, the two reasons that leads to such decision by a gambler is of he or she doesn't have any money to stake with again and if he is so confident that the bet is going to be successful. Other reason that leads to such action is when the gambler have lost all his money in the previous bet and he wants to use the last resource he or she has to make sure they win back some money they have lost (just equally a pattern of chasing losses).