all the chances you mentioned here are wrong. the chances are closer to 0% to remain safe in any of these places because in most of them (such as exchanges and particular web wallets) you don't even own your private key not to mention that so far all exchanges without exception had an expiration date when they started scamming their users!


these all depend on the way they are created, stored and handled. if it is all done correctly then they are the safest options so your percentages are correct.