The coins you earn from each run is neither just for show nor recruiting runners or purchasing new skins. Beyond considering it as an indicator of how well your run ended up as well, its more important value comes with purchase options that can help your reach higher scores and earn even more coins. The “me” icon at the main screen offers some boards that provide more than an upgrade in your appearance, but the costs associated with it are much higher than what you can earn, especially if you are just starting out.
On the other hand, the boosts you can buy with coins via the shop, which can be accessed from the main menu, can help in increasing your performance and profits on your subsequent runs. While some of these items are mere temporary boosts that get consumed, what you would want to invest in initially, are the upgrades for the power-ups that you obtain while running. While the consumable boosts are best saved for later, whenever you are ready to break records, gradually upgrading the duration of each in-game power-up is worth investing in ahead of everything else.
Note that each of the power-ups can be upgraded up to 6 times and the cost of each succeeding upgrade will naturally be more expensive than the current one. While some of these power-ups offer more enticing benefits than the others, getting more upgrades for your money’s worth is the best way to go. You are free to prioritize whichever upgrades appeal to you more, but know that each run comes with a random element that makes each power-up equally likely to appear.