I don't think so, if they aren't speculative investors. If they buy Steem they will have huge volatility and probably suffer from high inflation over time (but short term volatility is the bigger factor and the inflation does not guarantee a downward trajectory over any limited time period). Still, buying STEEM for beyond short-term really should be locked up as SP which still means still having high volatility but being locked in.

SBD is the best vehicle for non-investors IMO and especially for commerce (though it still pays interest so can be attractive to some investors). We just need to get things back to a tighter balance. With the market cap down 90% and SBD not having many uses, that puts a lot of stress on it. 90% declines can't be common and uses should improve. So ideally I see SBD as becoming far more stable and usable.

STEEM was intended in the design to be a sort of on-ramp and off-ramp for long term (SP) investors, not something to be widely used. In the real world though, not everything works out exactly as an original design envisions (we see this with STEEM now being paid out to users due to the "SBD stability" feature, so it already has another use). Still I see it primarily serving that role, eventually.