Anyone knows why the price has drop that much?
Let me bite as no-one seems to...
BTM price went down due to general alt market crash simultaneously with every market dipping few weeks ago.
It didn't find the floor so high as Poloniex disabled Trollbox, Bitmark's only current practical application.
This plus the issues with the BTM network at the time shook the investor's confidence myself included.
However I'm personally expecting Bitmark to get to Bittrex and elsewhere in the future so I'm not one of the weak hands myself...
... Speaking of which, is there any ways to store BTM apart from Polo atm?
Fair analysis I would say.
Regarding issues with the network, it has been stable is being fairly mined, take a look at:
As to how to store BTM ? You can keep it on your own wallet, here is a link to the wallets for the major platforms and source code: