That's a very naive interpretation. It's like saying people use cars because they have a window!

People don't believe in bitcoin only because it has a capped supply, they believe it in for a lot of reasons including but not limited to:
- decentralization
- censorship resistance
- cheap transactions compared to other payment systems
- having fastest transactions among payment systems considering both propagation and confirmation (aka being irreversible)
- provides highest security
- and of course because its price keeps rising!

Bitcoin is not a centralized shitcoin to have a centralized authority to give consent on changes. To be honest I'm a little surprised to see this question from someone account that is 5 years old!