Isn't this sort of thing generally seen as a bad idea? I know OP is not in the US, so maybe the rule are different.
OP, two big concerns:
1) As someone else mentioned, there is generally a fee to access cash vs just "spending"
2) Generally, at the end of the term, if you don't pay the whole thing back, you get hit for the interest for the whole term. So in the example given above, if your market value drops to $5k and you don't have any other assets to use to pay it back, you could potentially get hit for 18 months of interest on the $5k that you don't have.
Moral of the story...read the fine print.