Is Pyromantic Pact playable?

Basically the title. I'm no expert but while playing around in Path of Building, I find that getting the necessary max % fire resist to survive regular PP procs is an ENORMOUS investment for what amounts to:
* Infinite mana
* +20% fire dmg
* More ignite dmg

75% fire resist doesn't feel like enough given how often this goes off, so we'd want to aim for the cap of 90% such that we take just 10% max HP chunks. To get to that point, it seems like we absolutely need Unnatural Resilience, which is a 20+ point investment on my tree (or earning enough Delirium to jump straight to the notable). Those ~20 points can do so much work for output when used elsewhere, and ignoring PP lets us itemize out of strictly +fire resist on all gear.

All this to say, has anyone actually made Pyromantic Pact work in the endgame? It seems unplayable.

Lots of builds use it in endgame, easiest way is just to get rare jewels with +2% max fire resist, or the unique jewel 'against the darkness'. Pretty much all builds using it will aim to have 90% fire resistance (i.e. the maximum possible).

Once you have 90 fire res a life flask can pretty easily sustain any damage you take from it, recoup can also help.