You can't do what Jacob did and expect the same results. The Bible doesn't promise that. It seems like everyone who talks about getting whatever they want through prayer never seem concerned about how they could help others that way. It's always about themselves. God isn't stupid or unwise. God knows how to deal with selfish people. As James said,
(James 4:2-3 NIV) You want something but don't get it. You kill and covet, but you cannot have what you want. You quarrel and fight. You do not have, because you do not ask God. {3} When you ask, you do not receive, because you ask with wrong motives, that you may spend what you get on your pleasures.