I really enjoy having a phone that gives me full root control, and that is very similar to the Fedora (GNOME) distribution that I have on my desktop and laptop.
Buying a Linux phone from a pure Linux hardware vendor like Purism helps sustaining the mobile Linux ecosystem.
Yes, the Librem 5 is a bit older phone with some rough edges, but for me it is a really good phone. It gives freedom in the free software sense, and consistency with my Linux computers. I gladly accept some minor inconvenience to have a phone that respects my freedom and privacy.
I cannot foresee the future, but for me the experience on a Linux phone that I control is far more superior than any phone that spies on me and takes away my freedom, like Android or iOS, basically any phone from any manufacturer that disrespects me.