Billy was the bad guy in this movie...
If you think about it Eric really wasn't a bad guy before Billy made his little bet...he worked his way up to Vice president of a fortune 500 company and he was still fairly young. He obviously would've known how to legitimately run a company of that size as he would've done on an interim basis.
Billy technically was the bad guy in this...why would he deserve to be given a fortune 500 company after only getting his high school equivilent? Eric went through the same process as Billy, as well as taking business courses, and working his way to the top of the company. Billy gave nobody any reason to trust and have faith in him...how much money did he piss away on alcohol and skin mags. He never applied himself, he never went and got a job, his dad paid for his grades thinking that Billy would go to college and he never even did that. Billy was a scab on society who didn't deserve a mop job let alone the CEO of a fortune 500 company without actually doing anything.
Eric had every right to feel cheated, he was loyal, and to work as hard as he did only to have his diligence tossed aside for some little sh!t that went out of his way to embarrass himself in a drunken stupor in front of his father's associates...Billy was the villain in this film as he cheated a hard worker out of his job.