"Oh dear, dear. This isn't normal securities trading! Think you can assume your crypto exchange is basically competent and its systems well maintained? Think again. 'I know PHP – how hard could running an exchange be?' isn't the best starting point."
"You also can't assume a crypto exchange isn't going to mess you around. All manner of shenanigans that are completely illegal in proper security trading – bots painting the tape, wash trades, spoof orders, just front-running your customers – are completely normal in crypto. Your threat model is not just the other traders, it's literally the platform you are putting your money and coins into."
https://www.coindesk.com/2017-butt-bitcoins-joke/