Why can't we solve a mystery like the Loch Ness monster.
Quite surprisingly it is very simple to answer, no one is seriously looking for it. I mean that no one really believes that it is alive, so how is one supposed to find something they don't think is there?
We humans have grown accustomed to proof of something before it is found, since only bones of pre-historic animals were recovered, much of which date back thousands of years, we all make the decision that anyone who thinks otherwise is crazy.
People refuse to spend any money on issues that put their reputation at risk; anyone with an advanced degree, for example, would become a recluse if they go around claiming they've been abducted by aliens regardless of what they consider is proof.
Personally, I believe it is out there and until someone with the money/ and or resources comes along to perform a serious "animal hunt", it may never be found.
But you never know. A hundred years ago, people thought that some of the Chinese locals were nuts to see a black and white bear in which we now know as a Panda.
The meaning of life is curiosity; we were put on this planet to explore opportunities.