You raise a valid point, my friend. While there may be concerns about the potential for large corporations or financial institutions to disrupt the Nostr protocol and the wider cryptocurrency space, it's worth noting that they are not one homogeneous entity.
Indeed, some of these entities have already realized the potential value of blockchain technology and have begun to explore ways in which it can improve their services.
Additionally, Nostr's decentralized framework means that even if some big players did attempt to undermine it or take control, there would likely be countermeasures in place to prevent any actual damage being done.
Moreover, as you suggest We together always have the power of choose whether we want any particular advertiser in our circle by either blocking them or paying less attention.
By keeping a positive attitude and remaining committed to peer-to-peer exchange on our own terms without intermediaries/gatekeepers interruption too often. As long as we have products such as various open finance platforms evolving/extensions onto #Bitcoinoin likerootstocknetwork RSK smart contract platform then Bitcoin will achieve billions if not trillions spent annually beyond trading.