#1. security.
Depending on the point of discussion, Bitcoin network is secured. If you are worrying about your personal security then it has nothing to do about BTC network.
#2. non-fungable.
I wonder how you define fungibility, but from the definition on the internet,
fun·gi·ble
/ˈfənjəbəl/
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adjectiveLAW
(of goods contracted for without an individual specimen being specified) able to replace or be replaced by another identical item; mutually interchangeable.
"it is by no means the world's only fungible commodity"
It clearly stated that Bitcoin falls to this category. 1 bitcoin can be replaced by another 1 bitcoin without losing its value. If you have problem with exchanges blocking your account then you better not do any illegal activity and be aware that exchanges is not a part of Bitcoin network, they are just a third party company that take advantage of Bitcoin popularity.
Bitcoin can never really be great unless every coin is truly fungable. AND, to be fungable then coins must not be trackable. Yes, some "alt coins" try to deal with the above. But ALL mainstream cyrpto currencies especially BITCOIN need to start taking these issues seriously.
It looks like you are being confused on what fungible means.. specimen in the definitionn of fungible in the term quoted above does not mean the user but rather the item being used and that is Bitcoin.