Ok there was 100 million  TAG on the Tag blockchain then they were converted 10 billion new TAGS which are currently on the Stellar Network.
Thats 100 times more coins yet Tagcash is only offering 10/1,  you would have to be very very foolish to exchange your coins at that price.
I don't think its is illegal for them to offer such a ridiculous exchange rate, or is it ? 

Old Tagcoin doesn't have any real life purpose, while new TagCoin on Stellar is being used for fast and free micropayments within several mobile apps already.
Latest being an E-learning app, called Tag Learn, where 1 TagCoin can be used to watch 1 lesson. Great if you don't like monthly subscriptions.