Thanks for giving us a solid long-term view, with common sense added.
There's another reason for the "grab it while you can" effect: STEEM's success has been sudden, and sudden success reinforces "too good to be true" skepticism. I can see a level-headed person who got >$1000 in Steem dollars saying to himself, "Well, I won the lottery; I'd better cash in my scratch ticket. "
"won the lottery" is the go-to analogy for a sudden financial windfall. Not surprising that sensible folks act accordingly.
Myself, I've put my rewards into more STEEM: i.e., I've used them to power up. But then again, I'm something of a fool ;)