If I decided to save bitcoins in bank, how will deposit rate be changed compared to dollar or other currencies? Will it have much lower percent?
Its sad to say but there are no bitcoin banks existing online. If you want to earn then just hold your bitcoins in your wallet and wait for an inflation. That way you will get more profit out of your investment. The only way to save in banks is to convert your bitcoin into fiat currency and then deposit it on banks. But holding bitcoin is much profitable than savings on bank.
Correct. So, if you want to invest your bitcoin OP, the only option that you have is to invest it on the gambling sites or to those HYIPs out there, but it is not really that recommended because most of them always turned out to be a scam in the end, so, if I were you, I will look for another way to multiply your bitcoins while you are saving it, because just Holding your current amount of bitcoin right now will be boring if you are not going to do anything, but to wait for the right time to convert your coin.
Like for example, why don't you try to do Signature Campaign or other ways to earn bitcoin in a legit way every week or in every month, never try gambling though, because I am telling you that it is not a really good idea.