IMO, one of the bigger considerations with investing in Cobalt in the US is... the US. As I said in the OP, I look at it as a high end gamble, which is why I only bought a little bit of USCO (at 0.71) just for the halibut.
The time for it to potentially go up is during the current administration. If any dems likeminded to the bunch that ran in 2016 are poised to get in either in 4 or 8 years, I'd likely get out of it, because they and their EPA administrator will certainly be gunning for that kind of mining and production. Either to eliminate it or regulate it more than it already is.
Under Trump, there's a chance that regulations might be eased, which would create at least a short term pop. Of course that means keeping a pretty close eye on it if it's in your portfolio. Otherwise for set it and forget it, Mike makes good sense with an ETF.