I think that when a person comes to power, he becomes of interest to the powers of evil which, unlike the powers of light, do not observe the spiritual 'free will non-interference without invitation' law. So the more powerful a person becomes, the stronger he needs to be, to resist the powers of evil and be a Mandela rather than a Mugabe, perhaps?
Absolutely. Same goes for anyone on the 'mystic' path — it's really, really, psycho-spiritually dangerous, and not something to be undertaken lightly. Thankfully, most self-declared mystics are minnows in the pool.
Or put another way, you make your mark and the demons will come looking...
As an analogy, when I did my Reiki training, I was informed, absolutely, that 'Reiki energy' was the equivalent of the Holy Spirit (so you can imagine that, for me, the Reiki bus hit a brick wall right there) and we were all informed that it was impossible for a Reiki practitioner to injure anyone using Reiki, because Reiki can do no harm ...
Which is a staggering piece of ill-informed nonsense when one considers that the founder was a master of the martial arts, was a Tendai Buddhist, was a practitioner of Buddhist esoterism and occultism, studied 'Shugendo' which has a long and rich history, performed various training exercises on Mount Kurama, a place which is deeply steeped in the psychological training of the warrior mind ... and that in most 'old' martial arts there is a technique called 'reiki-no-ho' which utilises the exponent's ki/chi energy to completely overwhelm, suppress and/or bend the opponent's will to one's own design... all done before the single 'kiri' killing stroke/strike.
So I would rephrase the statement to read, 'the contemporary reiki practitioner, having achieved 'mastery', cannot hurt anyone because he/she couldn't summon up the energy necessary to do any real damage to a wet paper bag. However, the dedicated practitioner, undertaking the necessary and severe austerities, both physically arduous and psychologically dangerous, learning exercises and techniques of collecting and focussing energies, can actually do a significant amount of damage if they set their mind to it ... and has glimpsed into worlds that the average western practitioner does not even dream of ...