Bush was a horrible president, and Obama is a horrible president?
Those are matters of opinion. Millions of Americans believe that G.W. Bush was a good president, and millions of others believe that Obama is a good president.
In my opinion, it is way off base to claim that "we screwed up when voting."
When a politician is elected to office, whether or not he will do a good job is a toss up. A president's performance is, in a large part, dictated by a wide range of unforeseen variables.