The correct term is satire. And this is a brilliant example of it.
The entire conceit is that the hero of the story puts in minimal effort and is so overwhelmingly powerful that he defeats his enemies in one punch, and is horribly dissatisfied with it as a result because he never feels the thrill of battle, despite how promising things might seem. It eviscerates the clichés that plague the shonen/seinen genres.
And all the while, tension is maintained, because we the audience keep wondering if at some point...one punch might not be enough.
One thing has been made clear, repetition and dedication is key to becoming more than what you started as. Saitama worked "hard" to become superhuman, crab-guy ate too much crab and became a crab guy, Genus worked hard on his own theories and cracked the fountain of youth and genetic manipulation.
In contrast, Genos went for the shortcut and became a cyborg. He's super powerful, but didn't work for it. Correspondingly, he's been getting his ass kicked every episode so far. Those who dedicate themselves to a particular task are stronger or produce stronger underlings that he's no match for. He doesn't believe that Saitama could have achieved that level of power from basic training, and limits himself as a result.
As dumb as this series is, perhaps it is too sophisticated for you. Perhaps you'd better enjoy one of the three alarmingly-identical shonen harem series this season.