There is a rumor / people say / just one person wrote: It could be that his parents did most of his work, maybe also class-mates (he explained he was lazy and preferred playing videogames all day, he even missed school because of this). Then, probably all he had to do was memorizing data without understanding its meaning. Learn an easy mathematical formula, use it, the end. Make up theoretical solutions in a business test about a hypothetical problem, you get good grades as long as you write a lot and understand the basics. And if everyone around you is even dumber than you, you win.
I won't doubt Phil/Dave/Tom was good at school, parroting is easy and he has an absurdly good memory for useless facts. But school is nearly always theory, but praxis is always way different and this is where he fails hard. He was fired from everywhere as he can clearly not do anything on his own, is obnoxious and fails to use his knowledge properly. As can be seen in his current "job".
His education was wasted. Furthermore, maybe his education is sabotaging him as he literally things everything he does is always right, because he is valedictorian Phil Burnell, Champion of Wallet.