I don’t refer to script kiddies or Nigerian scams, but even a script kiddie have the possibility to hack a phone, as seen in the past. Also several databreaches with hundreds of thousands of sensitive data, including bank and medcal data, which were leaked in the past from Apple, MS, FB and Google, show what I say, mobile phones are far from being secure devices, especially if they are of large companies that look more at their own income than at the security and privacy of the user. At least, I don’t have any important data in my phone and I recommended everyon to do the same. If it is a workphone from you work, it’s different, than the risk is for the company, no yours, because of this, most use the kiosk mode, which with you can connect only to the sites admitted by the company.