The still-popular app game clash of clans cost you more than $12.000 if you choose to buy their in-game gems to build everything, I have seen a lot of people who have chosen to pay most upgrades with real money, instead of earning the upgrades in the games. Without gems, it will take 2-3 years to max everything out.
People who choose to pay for upgrades are the one who keeps the game going, without those paying costumers, the most game would close down, or stop eventing new things. Its only 1-3% of active players who choose to spend money on those so-called free games, but its thanks to those few people that game developers keep adding new things to their games.
I had a moment in life when I was travelling a lot and played a spinoff called clash of kings, which gave me some insight.
The players could be divided into casuals and donators. I was a casual, playing for fun for maybe 2 hours a day. A hardcore donator would be online 18 hours a day. When he was at work he had the game emulated on a computer, while travelling he'd use his phone, at home he'd play on 2 or 3 accounts at once on his computer and his phone at the same time.
A casual usually didn't spend any money, but he would quickly find himself being a victim, a farm for a powerful donator. The game made you feel comfortable for a while by adding barriers, which made you untouchable to powerful people, but after a while those buffs would end and you had a choice.
Either you'd start donating and improve on your defences, or you'd be the victim. People who chose to donate fell into a spiral, where they had to go on to protect their investment. They did not want to fall victim to another donator, because they would make him even more powerful and almost impossible to defeat without spending a lot of money, so they kept buying powerups to keep up, and those were some serious money, because the game just kept going. It was made to go on and on. You had level 20, no problem, you still can go to 21. You have a mastery? No problem, next level is mega mastery and then ultra mastery, and then... we'll think of something.
