I don't see it as an investment in a currency. I see it as a speculation on human behavior.
Here's my logic

1. Humans like to gamble,
2. We act like a herd
3. Bitcoin has the best advertising at the moment
4. It's has the most developers so could become something much better than others is.

So for those reasons I keep some "skin in the game" it isn't my biggest crypto holding Steem is. What's your favorite crypto?