Withen limits, anyone could build a radio controlled model aircraft, especally as the control gear can be bought off the shelf.
But, if anyone thinks that that is a UAV, then we are more in need of mental homes then I have thought in the past.
There are many things which a UAV must conform too which a radio controlled aircraft simply cannot fulfill.
If You do not belive me, go out tho the park on a Sunday morning, and have a look, then try and imagin these things carrying wepons, and/or full EM spectrum cameras and doing it reliably, and safely.
It's that area alone where the millions will be spent, yes I said millions!!!