And it's to keep your local Busker card in your inventory. At least until you're ready to let go of it.
Fans Are Precious
and if you don't know, they increase your mission's MAX STARBITS rewards. That's enough reason to have you stack Fans.
But there's one more use case for Fans and it's for
Mission Requirement
As you know (you'd have to be living under a piano to not know this one) Missions in Rising Star have requirements. The most difficult one is the level requirement, but early on, if you're not a big investor and haven't bought any packs, or if you HAVE bought packs but have been on a series of bad luck (like me) and have gotten only instruments from your limited number of packs (oh, dear), you might be struggling for the Fan requirement in the game.
Newbies usually fulfill the required number of fans with drunks and such which is usually the go-to when you want to access higher missions as a newbie with zero investment.
The Busker Card
Gives you 10 Fans and 1 Skill. It is a starter card that is given to any player upon account creator, but it is not an actual card on the blockchain in your inventory. Once you change your avatar card (the default is The Busker, duh!) it can never be set as The Busker again and more importantly the stats are lost. Not a big deal if you've got a ton of fans, but I figured it might mean the access to higher missions or not for the new player.
Also, I said that you wouldn't be able to set it back as the busker again, but that's not entirely true. See, the Common "The Busker" card is not an actual card on the blockchain, but there's a "Founder" type of The Busker card out there with only 14 print limit (which has obviously been reached) and it cost thousands to get them due to their rarity!
Yea, technically, you can buy that and set it as your avatar card which I wouldn't really recommend, honestly. If you really wanna go for SUPA RARE cards, I guess aiming for Legendary 'people' cards is the better alternative and much more doable.
Hope that helped.
Stay safe and never stop busking...
Cheers~