Re: How the hell
It's a combination of the policy of money-printing (dubbed "quantitative easing" to make it sound better), financial repression with artificially low interest rates and the wealth effect.
Freshly printed, or at least issued, money gets dumped onto a market where interest rates are held low to encourage investment in assets other than government bonds, which you can't buy anyway because the central banks are buying them up. This pushes hot money into speculative assets such as shares, currently even more so as money is returning from emerging markets in anticipation of an end to easy money. The rise in share prices, in much the same way as rising house prices do, makes people feel wealthier, thus more likely to spend money (they don't have, but, hey, at current interest rates it's better to spend it now than watch it depreciate, or if you're in debt snuggle up with the thought that your debts will be worth less tomorrow). It's the economic equivalent of perpetual motion and just as much a myth.
Oh, but don't worry about not getting a piece of the action: your savings bank and pension plan will make sure you do.