Why? Because there are so much more technologies that are safer, more reliable than BTC is or any other network of cryptocurrency. :]
It is not right to say that Bitcoin is not reliable, so far Bitcoin has not been hacked. Only the stock market was hacked. I'm also curious about the other coins. Bitcoin does not say there are no shortcomings, eg 51% Attack and Double Spending are still not resolved. But I believe that Bitcoin is evolving.