Recently i've been thinking about why are we collecting coins in a freemium app/any video game. Probably its related with the arcade saloon culture. You can't put your own money in a machine because of some security and maintenance reasons so you'll need a unified currency to spend. The most simple solution is to invent a replica coin which replaces the regular money we spend. So when you go to a saloon, you exchange the money with a coin, (5 coin for 1 USD) and start spending time and coins in front of arcade machines. (which is very similar to app store model).
I remember my childhood as an arcade saloon addict who visits the one and only arcade saloon in ankara, turkey named as Fantasy Land. That place was the first place that i discovered many feelings like adrenaline, excitement, danger, socializing, competition, bankruptcy, richness, disappointment, victory. Also it was a place where best friends meet and spend time together analyzing games, becoming better for a specific game, discussing game characters, game plays, becoming opponents, becoming over competitive so that getting angry each other and next day make peace at school.
Every game has addicted players also masters and learners around who are wannabe's dreaming of becoming a master one day and beat every one else. Me and my friends stayed there in the dark, many years (that place was really dark!). Spent every free time also some illegal school time too and we trained and learned a lot. After some muslim feasts we specifically go there and spend money we collected from our grand parents and relatives (richness?).
There were a bunch of people who was literally living inside the arcade. When you go there, you always see him playing the game or giving tactics to players or talking about that video game. You hang around with them (socializing), beaten-up by them and learn. We were not afraid of failures, disappointments of a match. We were not afraid of masters beating us (danger). That arcade saloon had a lot of bullies around. Some of them threatened if i beat him in the game he'll punch me in the face but that never happened.
We started developing skills also started to spend less money on coins and play a lot more. When you become better, people notices that and wants to fight with you. Every time you fight with a new human opponent (competition) many thoughts go from your mind (adrenaline, excitement). Is his technique than me? Which character should i select to beat him? Will i win? If i lose i'll lose the on going arcade game. Many times you go to that saloon with a desperate balance which can be converted to 1 coin and you behave as optimized as possible so under poverty pressure, you become better.
On a lucky day I have beaten one of the masters in a MK3 fight (my friend can beat him too). This was the time i learned every master/human can lose a match, is beatable. That was the most satisfactory and the last thing i remember about that arcade saloon. "Beat the Master" achievement was unlocked for us (victory).
We won a lot of games, lost a lot of games (disappointment), spent a lot of money (bankruptcy) and learned a lot of things to survive in a dangerous dark social place (for a child).
The downside of an arcade game was it doesn't return you anything financially (not adressing slot machine or casino games here). You invest money, time and brain cells and all you expect is to get good time. I can define a game as "a loop of activity/experience that makes you forgot the realities and boring mechanics of the world which can be rented/bought by your coin/money. I think, the idea of collection of coin in a video game is to emulate this financial return. A game return you a bunch of digital currency (coins) so that you can spend this on your newly built farm or on an item or on a new character skill etc.
PS : In turkey we call arcade saloons, "Atari Saloon". Probably they named the saloons after filling them with a bunch of games released by Atari brand. I also don't understand the term "video game". I searched the roots but couldn't find anything.
PPS : Fantasy Land can't be held responsible for this story, events and history.