If the company go down (but it won't, because Bitcoin it's still too small) is your money they lose. What you funded in their account and all the gains you did not withdrew. Just like when it's your bank that go bankrupt. All money that it's not under your mattress is gone. The individuals running the business have no risk, it's their customers who are risking their money trusting it to a bunch of white collar gambling scammers
And that's why we have Bitcoin

True, all that I said is a big picture scenario, Bitcoin is by no means big enough to make a Company like Plus500 to go down. There's really no way.
So enjoy it, my friend

I like bitcoin. Plus500 will stay alive (I have no intentions to ruin Plus500 .. I like them they propagate bitcoin .. I only feel easy money :-) .. why not to hedge with Plus500 1:4 )