How about the owner of the wallets.(wallet company) is it possible to check your balance your account details etc..
coz you sign up and create your passcode etc.. and put some bitcoins to your wallets.

1 more reason to get your bitcoins is they will get or  hack your passcode to your wallet so be careful about your passcode to your wallets.

There's a lot of reason to hack your bitcoin but there's a few reason to protect your bitcoins. hmm correct me if I'm wrong.