The War on General Purpose Computing (2015) [video]
I've made it a personal rule that I would not pay to buy something I cannot own. Barring government regulations, if something does not give me full (theoretical) control of its functionality. Though, this is subject to some practical considerations, such as cost. If I can sufficiently limit the damage some unowned device can do (such as by not connecting to internet), and it is cheap enough second-hand, then I can still consider using it.