Everything dies at some point. Even the universe probably will. As for Bitcoin, it's currently technologically relevant, but we honestly can't know right now for how long it's going to be this way.
There's also a certain limit on the price of Bitcoin at any given time. The global economy can be monetized, and Bitcoin cannot be worth more than all of the goods and services in the world. Of course, the global economy can grow, but it does so pretty slowly.
It's okay not to set a strict limit on how high the BTC price will reach, but there is a ceiling for that. Moreover, having a target in mind can be helpful to decide when one is actually ready to use/spend Bitcoin, and not just hodl it.