Makes sense. I've bought a couple of batches of Steem this week, using fiat and via Ether.
I think earlier on in the year all coins were rising together, but now we have, as you say, the trading between BTC and the rest.
The upcoming BTC fork is interesting too, perhaps people are looking for a repeat of the BCC payout with Bitcoin Gold.
A few more weeks to wait and Steem should be rising again... hopefully!
Where did you buy the steem using fiat?