The perpetuity aspect is a good point, but the fundamental pitch of Watsi is "100% of your donation goes to a specific patient in need", not "100% of your donation goes into an investment account that will be invested in anything from oil to cryptocurrency (and things you might not necessarily agree with) whose returns will then go to a patient in need". The vast majority of donors donate to Watsi for precisely this pitch. Also if Watsi made this change, who would manage the investments? Wouldn't it fundamentally change the company from a small, lean, product-driven global health nonprofit to a socially responsible investment (SRI) company (which there already are many of)?