Bitcoin development is centralized. Decisions and the political marketing for them, are made by core devs whom other non technical people trust. Many of these devs have historic ties to Blockstream or other large institutional investors. This are the institutions with the funding to back research into and maintain bitcoin.

The only proof you need is seeing who stands to lose the most from bip300, Liquid, and how those connected to blockstream argue against it. But there is other proof too.

So i ask you, how are decisions to improve bitcoin made ? and how is this different than the college of bishops in Rome ?

Drivechain allows the free market to decide what bitcoin does, each user gets to decide, on a seperate layer fromncore bitcoin that remains mostly the same going forwards in time.