Like what? Self-improvement is the best long-term for his life and helping his family, because it will have lasting effects even if he loses the gadget tomorrow.
That sounds a bit hokey to me, under the circumstances. The value of his ability to stop time vastly outstrips the value he'll be able to contribute to either his family or society by studying a little bit more as a person of otherwise-average means.
So long as time is actually stopped, in a physics lab he could assist in experiments that should be physically impossible (consider how much effort has to be spent separating samples in quantum entanglement experiments). As a medical first-responder he could save lives daily by getting people to the hospital in zero time. In espionage, he'd seemingly be unstoppable. There are no shortage of immensely useful things he could be doing with himself.
Or, if you prefer, capitalistically speaking, rather than his societal value: If he is unique in this aspect, than as a resource, his services are worth billions. Less if hiding his ability, but still outstripping the earning capacity of a salaryman sufficiently that he could earn more in the time he's studying, than he will in an entire middle-class white-collar career.
Instead, he will marginally improve his standing in work and education by working overtime. He isn't investing his use of his ability, he's squandering it.
(Like, yes, he's quite likeable for it. He has some real himbo charm. Don't get me wrong. But...)