Ah, okay, so 98% of their Bitcoin keys are "hack proof". "Absolutely impossible" to steal or destroy. If you make an absolutist statement like that in front of any serious infosec expert they will probably throw something at you 
. Security is not an absolute thing. I'm not saying you shouldn't trust Coinbase in the same way you get on a commercial airliner and feel safe, but never say "never".
(As a side note, in case anybody was wondering: yes, I am in this exact business with Haypenny. Like any digital currency we have to worry about infosec, and we take very strong measures to secure our data including keys physically held by two different roles that are kept physically apart. However, we also have mitigation plans in case of a catastrophic hack that would limit damage to a tiny fraction of customers).
. Security is not an absolute thing. I'm not saying you shouldn't trust Coinbase in the same way you get on a commercial airliner and feel safe, but never say "never".(As a side note, in case anybody was wondering: yes, I am in this exact business with Haypenny. Like any digital currency we have to worry about infosec, and we take very strong measures to secure our data including keys physically held by two different roles that are kept physically apart. However, we also have mitigation plans in case of a catastrophic hack that would limit damage to a tiny fraction of customers).
There's no such thing as being hack-proof—just like humans aren’t immortal. So, what’s your point here, and what do you suggest regarding the topic you raised?
Financial institutions, like banks, have similar practices where all deposits are insured but only up to a certain limit. It’s the same with crypto exchanges, where a portion of deposits is insured. Even laws aren’t perfect. No government can insure all Bitcoin held on an exchange; their role is to assist in investigations if a hack occurs to recover lost funds.
The fact that 98% of the assets are in cold wallets makes hacking difficult, though not impossible. As traders, we must be aware that this is all an exchange can offer. If that doesn’t sit well with you, then perhaps it’s better not to use an exchange, as they generally follow similar standards, with only slight differences in how they implement them.
If you don’t trust the exchange, then simply don’t use them—store your Bitcoin in your own wallet, where your keys are your control.