One key element to remember is that Batman was born from tragedy. Unless you happen to have your parents killed in front of you at the tender age of 8, you will probably never have the all consuming rage that drove Bruce Wayne to become Batman. Regardless of the seemingly limitless financial stream, he still had to push himself to near superhuman levels of strength, fighting skill, mental performance, and self-discipline.
Strength
By my account, Bruce Wayne is incredibly strong. He is often depicted in comic books bench pressing a weight bar with some 5-8 large weight plates on either side. Assuming that most large weight plates are usually 45 lbs (20.45 kg) and he is using a standard 45 lbs Olympic bar, Bruce Wayne would be bench pressing somewhere in the range of 495-765 lbs. This is within reason for peak human performance, but it does not account for the fact that he is often performing multiple repetitions. It also doesn't account for the fact that his muscular frame does not resemble that of a weight lifter who would be able to press that much weight multiple times.
The same goes for Batman's leg strength. The world record squat is 1250 lbs (568.18 kg). It is presumed that Bruce Wayne can squat a weight similar to that, yet he doesn't have the massive tree trunk legs that power lifters have. There is a scene from Batman: Dark Victory where The Hangman has lassoed Batman around the neck and he is left suspended from a roof. Disregard his neck strength, it turns out that he was wearing a metal (possibly medieval) neck brace. Batman was still able to push himself up and back over to the top of the roof. So basically, he was able to push some 210 lbs (assumed weight) up into the air approximately 10 feet from a dead stop. I'd recommend trying that with a bowling ball a few times and then tell me that you think you'll be able to do that with your entire body. This is truly one of those “no way” moments that is immediately followed with “what a badass”.
Fighting Skill
According to an online posting, Batman has mastered some 127 different fighting styles. I don't think you have to go that far, but you are going to have to be incredibly proficient at 10 or more. Just to name a few, I'd say that you'd have to master Jujitsu, Hapkido, Ninjitsu, Judo, 52 Blocks (jailhouse rock), Aikido, various forms of Kung Fu, and straight-up back alley brawling. You'd better be prepared to dedicate 10-15 years to even get a chance to ride the bench on Batman's team. Basically, you are going to need to be able to beat Bruce Lee, Chuck Norris, Chuck Lidell, and about 5 other UFC powerhouses all at once.
Mental Development
We already know that Bruce Wayne was the son of a doctor. So, it's a given that he has a general idea of first aid and the processes of the human body. Yet, he had to train to become the great detective and tactician that he is. He also seems to be pretty good with computers, chemistry, and many other disciplines. Regardless of any other factors, you can't fake this. This would mean that he has to read at an incredible rate and completely retain it. It is entirely possible to have planned strategies to combat situations, but you still have to remember them. Even still, you would have to have a pretty good mastery of all of these disciplines and some pretty big stones to trust in your abilities to perform required actions as required. It's safe to say that you're going to need an IQ that is somewhere in the genius range.
Self-Discipline
Ultimately, none of this would be possible without the amazing level of self-discipline that Bruce Wayne possesses. Keep in mind that his childhood was shattered and rebuilt on his feelings of helplessness, anger, and vengeance. You would literally need to get to the point that you could climb Mt. Everest, cruise through Navy Seal training, say and do everything without having any fear of doing it wrong, and have complete confidence in your physical and mental capabilities.
Then, and only then are you ready to start thinking about the other things needed to become Batman
