I have yet to even meet a single "acid head" based on the definition of the word.
Well, I've known maybe twenty people who fitted that description at some point in the past, and they themselves have known many more. These are people for whom regular tripping forms an important part of their lives, both creatively (all are artists and/or musicians) and socially.
I should add, though, that most of the guys I'm still in touch with are now more inclined - when possible - to use other hallucinogens (such as ayahuasca and mescaline) instead of LSD. Partly, this is because the environments in which they trip have changed over time (fewer illegal raves, more communing with nature), and partly because the quality of acid available these days is apparently not what it used to be.
The stories of people jumping out of windows and such are largely apocryphal.
But only 'largely'. Alongside those I've mentioned who did come to actual harm:
I've seen a guy wandering towards a railway track, saying he wanted to hug a train (thankfully, someone else had something shiny with which to distract him).
I've seen someone get pulled from a car by his friends after attempting to drive off whilst completely out of his mind, convinced that, despite his inability to see the road, God would ensure his safe passage.
I've had to pick up a friend of mine (along with his passengers) who convinced himself that his car didn't need fuel because "it runs on love", and so refused to stop at a service station.
I've had to confiscate a friend's toothbrush and ban him from going to the bathroom without a chaperone because he'd brushed his teeth seven times in less than an hour, and his gums had started bleeding.
I've had to convince the same friend that telling off an extremely large, heavily-tatooed, and distinctly menacing Scotsman for selling him a 'dodgy' bacon sandwich would be an error, not least because there was nothing wrong with the sandwich - he just wasn't hungry. (This friend in particular has a habit of doing and saying very odd things whilst tripping - curious because, when sober, he gives the impression of being the most ordinary, conventional guy you'd ever meet).