This is super creative and looks like Google is on a mention with the whole alphabet concept. This has to be one of the best new GTLDs I have seen so far. The first 3 letters of the alphabet and the last 3 are the domain name. Petty awesome. I see they sell pretty often.
Some of the most recent sales include : hah.xyz and sit.xyz
In my opinion I really liked the creativity and cleverness of abc.xyz but I just don't see value in the rest of them. But people are indeed paying some insane money for the short ones.