The biggest threat to Bitcoin is capture dev capture. Done right you won't make changes to the code that people disagree with immediately. You will make small, incremental changes that seem insignificant in the grand scheme. Shift the overton window, boil the frogs.

Ultimately the rules of the network are underpinned by social consensus, and there has been no point in history where mass social consent is invulnerable to manipulation. Being aware of this is critical to defending Bitcoin over the span of decades to hundreds of years.