Bitcoin mania is in full swing - with no end in sight

But bitcoin has regained its mojo this year, helped in no small part by a decision by US regulators which allowed Wall Street to move more heavily into cryptocurrencies. In January, the Securities and Exchange Commission gave the green light to the first exchange-traded funds that hold bitcoin to be sold to the public. This move allowed mainstream investors to buy and sell bitcoin as easily as shares, without having to trade on crypto exchanges and pay hefty transaction fees. And investors have embraced these new "spot" bitcoin ETFs with relish, pouring some $US15 billion into funds managed by the…