On the contrary, ICBMs as manufactured are inherently orbital. Most of the trajectory of an ICBM is above the atmosphere, and the range is long enough that it’s definitely an ellipse, not a parabola. The biggest problem is that any closed orbit which intersects the surface of the Earth once (at the launch point) is going to intersect the surface of the Earth again, and soon (after less than one complete orbit). If you want something to go up and stay up, then you need to rocket burns (which may or may not mean two stages): First, you fire the rocket once at launch, to put it into a ballistic-missile type orbit that’ll intersect the Earth. Then, when it’s as high as you want it, you need to fire the rocket again, to change it from a high orbit that’s going to get lower into a high orbit that’s going to stay high.
And Jurph, I’ll defer to your expertise on the question of how hard it is to actually get things to work. But the calculations to find the orbits and changes of orbits are very straightforward, and could in principle be done in a few hours with pencil and paper using no more than a high school education (I say “in principle”, because most high schoolers don’t particularly understand what they’re taught, but they’re given all the tools they need).
By the way, Nanoda, my university is involved in the construction of one of those cubesats. The price figure of a few tens of thousands of dollars is in principle accurate, but no cubesat has yet been launched. They’re a secondary or tertiary payload, at the mercy of the whims of the primary payload launcher, and the Russian company which was contracted to provide launch services has proven to be rather unreliable.