it takes hundreds of hours of hard to work to achieve something special and get that nice shot of dopamine from your nervous system rewarding you for a job well done... or you could play one of these games for like 30 minutes. why spend ten years leveling up your coding or drawing or composing skills when you could get to be a wicked cool level 35 5-star awakened fire monster in just a few weeks (or like right away if you throw down some cash)??
they've done a good job capturing the addictive aspect of Diablo (which i think should be called Dopaminecraft to fit with Starcraft and Warcraft). play over and over and over again not because it's fun really or you're doing anything different, but because you're going to see your characters' numbers go up and up and get that occasional epic drop that makes you go WHOOOAAA just because the text is in a different color and the number next to the item is bigger than the last one you got.
it's so sad that this works and our minds are so weak and easily manipulated. exploiting these natural weaknesses for profit (as marketing, sales, advertising, junk foods, sugar drinks, casinos, drugs, and others also do) seems really immoral. still... i'm glad Summoner's War exists and have become pretty attached to my little monsters. i hope people find ways to harness these manipulative powers for good like working in useful education or side effects while playing. or just focus games more on strategy and skill mastery and less on time played and money spent.