School Choices neither solicits nor accepts tax-payer funding. The cost is quite low, and could be born by any community group, and a great many private citizens. Now, on to your message. Personally, I have dedicated my life to improving the educational prospects of all children. I wouldn't describe my motives as altruistic, though.
Altruism implies an indiference to one's own interests, and perhaps self-sacrifice as well.
But I have chosen my present profession specifically because of my own abiding interest in education and the welfare of children. Of all the activities in which I could engage, this is the one I find the most personally satisfying. So, while I don't have any of the ulterior motives you're wondering about, I'm not really an altruist either. It would not be meaningful for me to swear to this on the bible because I am not religious. All I can give you is my word, and since we do not know each other you would be justified in treating that word with caution.