SBD was intended to be pegged to $1 USD so I'm not surprised if it's returned to this level. The fact that it shot way above $2 a week or so back was insane and there was no way to really trade it on Poloniex since deposits and withdrawals were disabled at the time.
Either way, I'm not sure if it'll actually rise in value like STEEM will, because it's not intended to. Of course the market does what it wants to. I'm just not going to invest in it beyond the rewards I receive from the platform. Then convert that over to SP :)
Yes, the core purpose of SBD is to be pegged to $1 USD but it has increased and as it is being traded, I am sure the price will keep fluctuating. It could go well above expected $1 USD.
And regarding investing in SBD, it is good to convert it into SP on this platform but some people might be interesting in SBD too as prices are changing :-)