Designing your system to fail gracefully without financial consequences is far more important than designing it not to fail or get compromised.
OK, so if I read this correctly:
It is almost six months ago that Bitcoin Central, the main Bitcoin exchange in France, shut down after losing tens of thousands of dollars to an online attack. The attacker managed to get in by breaking into the exchange’s virtual private server, allowing them to access its online “hot wallet” and withdraw all of the funds. ... But now, after nearly five and a half months of downtime, Bitcoin Central is back online.
your utter incompetence cost company the content of hot wallet + 6 months of downtime.
And now you feel like you're in position to lecture anybody on security....
Dunning–Kruger at it's finest.