Arguably, that's better than aiming for a perpetuity. By economizing on starting capital, you can set up substantially more of these, and you avoid the pathologies of perpetuities (eg. the Hershey trust): if after 30 years a charter house actually does completely run out of money and it can't fix its finances, then maybe its time has come and it's a good thing it can't simply be a trust fund baby rentier.
Given how many communes or nonprofits go bad, it's good to have some sort of accountability to outsiders in the form of 'needing money'. (The recurrent debates over the Wikimedia Foundation's ever expanding budget being a good case in point. Are you impressed by what they have done with the many millions of dollars they've gotten in the past half-decade or so? No? Then it doesn't seem likely they're going to impress you very much more if they become so wealthy that they can operate forever off interest and have to care even less what any donators think...)
Given how many communes or nonprofits go bad, it's good to have some sort of accountability to outsiders in the form of 'needing money'. (The recurrent debates over the Wikimedia Foundation's ever expanding budget being a good case in point. Are you impressed by what they have done with the many millions of dollars they've gotten in the past half-decade or so? No? Then it doesn't seem likely they're going to impress you very much more if they become so wealthy that they can operate forever off interest and have to care even less what any donators think...)