Because you haven't achieved that ideal?
Because I have. I'm well aware that I'll always have room to grow (I've pushed against a lot of my edges, and found that they "give"). Maybe, from the quote you gave above alone, that would mean that I've self-actualised: I recognise my full potential (specifically, I recognise that it is unattainable by nature of potentiality!) and keep pushing anyway. Going beyond that, I certainly tick all of Maslow's criteria. But I don't think they are sufficient to fulfil his definition (and I don't think that his examples - Maslow listed many historical people who he believed to have self-actualised - help the matter either). Perhaps it is language that failed him, and he lacked the tools to describe the self-actualising state. I'm a big fan of the actualising tendency described by Carl Rogers (who was doubtless informed by Maslow, over the years in which he wrote): the idea that an emotionally healthy and functioning human will, given sufficient nourishment, tend towards their own betterment: the goal that might be called "actualisation". But it's not my opinion that anybody ever reaches it. To me, the quest of actualisation is like trying to walk to the horizon: no matter how close you get, it'll always be as far away as you can see... and I suspect that a characteristic of emotionally healthy people is to understand and accept that, and keep on walking anyway. And I wouldn't call that state "self-actualisation".
One person's heaven is another person's hell. This description of self-actualization sounds a lot like the concept behind Siddhartha's goals of finding nirvana. I've thought a lot on the idea of having nothing that can upset me throughout my young adult life, and I keep coming to the realization that having nothing to solve would eventually bore me. I personally thrive on change. Being a monk would drive me insane. However, the idea of striving for my absolute perfection would absolutely tear me apart! Never being happy with where I am at this particular moment in time would be to spend the majority if not the entirety of my life never knowing the contentment of living in the present.
Well said. But for me, striving for better-ness does not imply that I an not happy with where I am right now. I'm comfortable and satisfied with where I am (not least because I know which direction I'm heading in). And when I look back over my life, and see the times at which I hadn't yet made so much of myself, they're generally still pretty good: I have, so far - on average - lived a happy life. That's not to say that bad things haven't happened; that I haven't had hard times and emotional struggles. Just to say that I've typically been happy throughout, and that I've learned to do better and better and finding happiness.