Because I've tried it out with a couple of coins they offer, egold, yone, and one or two others.  As I said, the interest does show up in your account and you can claim it with no problem.  I've done it before, but the value of those coins is so low to begin with that it's not worth even doing it.

I have no idea whether any bitcoin would get stolen if you deposited it into one of those investbox schemes, but I just don't trust it.  Why?  Because I don't know what they're doing that they can promise you interest on bitcoin.  My suspicion is more that I wouldn't get paid what was promised than yobit would run off with the coins, but who knows.  It's yobit.

I don't want to advertise for yobit now that they changed their signatures.  And from the services thread I'm hearing that the payment for the past 7 days is all screwed up for members that changed their sigs before the payment button got unstuck.  I'm going to wait to see if my last 2 posts get paid for and then I'm out.