I am not now a Pentecostal or charismatic. However, I was the first 15 years I was saved. To me it is a shallow doctrine, and mostly experiential. I prefer to rely on the Bible for my doctrine, and let the Holy Spirit, who is NOT an extrovert, lead and guide me!
In fact, a cult, the Oneness Pentecostals are the ones who perpetuate this non-biblical idea that you aren't saved if you don't speak in tongues as well as a bunch of other heresies, like not believing in the Trinity. I have no problem fellowshipping with Pentecostals, even if they tend to sometimes look down on people who haven't had this so-called second blessing.
I'm not worried about denominational issues that are not central to salvation. But, as I said, Oneness Pentecostals have added to the gospel. That does affect salvation.
And I did once believe I was baptized in the Holy Spirit. But it became apparent I was lying to myself and God. Just because something was written in the Bible, doesn't mean it applies to us, today.
As for why Pentecostalism has lasted for 115 years, I believe that emotionalism sucks people in, plus charismatic leaders suck people into their sect. But no, most Pentecostals are not bad people or even deluded. And God is dealing with us all, and he knows where each believer stands, and where they need to change to be transformed.