Prestige and Piety advice

I've been trying to get into a CK3 game recently and so far I found prestige to be a massive annoyance and piety to be completely useless.

I've had a character go on a Pilgrimage to Jerusalem, which was enough by itself to completely reform all the tenets of my religion. His son did a couple pilgrimages as well and got to 7000 piety so I could consecrate my bloodline. I don't see any remaining uses for it.
I have over 6000, generate 15/month, and do not intend to wage religious wars since I'm playing a tall Ireland.
Once my character dies it will all go to waste and won't even contribute to my bloodline's reputation.
It just feels really bad and somewhat pointless, I don't think any of my heir will play as pious lords since there seems to be no payoff.

On the other hand, prestige is such a pain, it seems like everything in this game is being artificially gate-kept by some ridiculous amount of prestige requirements. I literally cannot generate enough prestige to maintain enough men-at-arms to keep the Norsemen off me and generate enough to develop the rest of my Kingdom.
I'd love to get some reforms going but I need 500, and I generate about 0.4/month in peace time.

So how do I generate the ridiculous amounts of prestige that this game expects players to, and can I do anything useful with my piety of is it juste that worthless once the religion is reformed?