you see you say decentralized and miners in same sentence,
Chinese miners is not one cohesive group. Not all chinese miners do the same thing, not all miners do the same thing. There is no one cohesive group that defines "chinese miners". The chinese miners are decentralized, each individual person can do whatever they want. On the other hand, developers are a cohesive group as there is really only one software that defines the network. There is only one software, so whatever an individual developer does, the entire cohesive group produces only one thing that represents "the developers". That is centralized, chinese miners are less so.
why do some chinesse miners would have a majority say in it,
They don't. There is no single miner which has a majority say in anything. For any consensus change to be made, there must be consensus, i.e. nearly all miners (not just the majority) must agree to enforce the new rules. Likewise, nearly all full nodes must also enforce those new rules.
when devs should be ones making decision,would you think that miners are smarter and know whats better or someone who develops and patches the code ?
No. No one group should be making and forcing decisions and changes onto everyone else. The miners should not be forcing users to a certain change, devs should not either.
Since the way i see developers are independent,miners will chase profits and whatever fill pockets for them.
Miners are independent as well. Again, there is not one cohesive group of miners that decides what all miners must do. However, by virtue of there being only one software, there is a cohesive group of developers that decides what the developers do.