Man, SBI is great in so many ways! It provides an upvote for life, but also it makes you feel good for giving and it makes the receiver feel good for the gift. And the units add up to both as you mentioned.

The interesting part, as you said, is that someone has to gift you the first unit, so you can enter the system. I'm not sure if it's possible to gift yourself an unit, and to be honest it would lose much of its do-good charm if you could/would.