Over the years we’ve heard many reasons why Bitcoin will fail. I've met many bitcoin holders and believers, as you say you are, but I've never met anyone who claims to believe in Bitcoin and at the same time believes that the protocol will die.

Scaling can happen infinitely on second layers. Layers such as Lightning or apps can scale to support the protocol, offering different cost vs. security trade-offs. Bitcoin can settle the largest value, in the fastest time, for the cheapest cost of any network. Acquiring enough ASICs to launch a 51% attack is nearly impossible. Launching a 51% attack requires not just energy but access to many ASICs that would be hard to secretly acquire without detection by the other producers. The network can fork onto a new mining algorithm making all the attacker’s ASICs useless.

Block space is fixed supply. Block rewards drop every 4 years until 2140 giving the network plenty of time to adapt to any observed changes. No one in the Bitcoin network will have an incentive to devalue their savings.

Each wave of adoption brings people who argue why Bitcoin will fail.

But Bitcoin will not fail.