A Satanic priest can be valid, as can the mass he says. A Catholic who voluntarily and knowingly uses him or attends his mass will go to Hell, no doubt.
You don’t run ahead of God. That’s putting your personal will ahead of His. It’s the sin of presumption if done knowingly. A humble man, even if he’s sure he’s meant to be a bishop, will not actively seek consecration. He can confide in his superiors or confreres, and, indeed, ought to do so in most cases. “In the mouth of two or three witnesses, let every word be confirmed.” II Cor. 13:1. Fr. Pf., having sought those witnesses and not finding them, rather, the contrary, has placed his will over that of Our Lord. How sad. Nothing good will come of it, either for himself or the faithful.
It’s an awful experience to discover you’ve naively received a doubtfully valid sacrament from a man who may not have been a priest—-no way to find out! I refer to a general confession made in an effort to return to the Church. I prepared very thoroughly and went into the confessional in fear and trembling having not been to Confession since age nine. I was then in my early 40s! I discovered six months later that the man probably wasn’t a priest! I had to use the remaining three days of a retreat to try and re-confess everything. For over a decade, and even now, occasionally, an omitted sin will come to my mind. This is not good for one prone to scrupulousity.
I’ve been “baptized” four times under similar circuмstances, Confirmed twice, and given a doubtful anointing for Last Rites, again, bad shepherds.
I can fully understand why some Catholics choose “home-alone-ism.”