Maybe you answered your own question?

A:
I do think it is a rather useless asset and does represent some awful impulses: greed, corruption, lack of transparency etc.

Q:
If only a part of a larger basket of securities, I think why not allocate a sliver to calm the FOMO?

If one wants some "zip" in a portfolio, the more sensible way to do that is commonly to invest in things with uncertain outcomes but at least a chance of earnings. Generally you can find lots of things with a big but uncertain upside attached to a moderate downside, even among things with demonstrable value as investments because they can (or at least) might earn good money. Heads I win, tails I don't lose much. Sufficiently asymmetrical outcomes combined with appropriate position sizing removes the need for a conventionally mandatory Rule #1 test.

Per that reasoning, there is a pretty good case (better than bitcoin) for having a very (very) small allocation to literal lottery tickets. The chances of winning are terrible, but the upside:downside ratio is spectacular!

: )
Jim