First and foremost, electricity is dangerous. No need for me to reiterate it, though I just did. That said, I have seen licensed electricians - having an IQ that would rival a dolphin, or worse - quickly, efficiently, and safely install wiring, boxes, panels, etc. in residential and commercial buildings. In other words, it isn't rocket science, but you have to be properly trained and/or familiar with which you're working.
Unfortunately, forums such as these are not helpful when it comes to learning anything beyond the remedial basics of electricity. You get knee-jerk reactions from the "if you have to ask..." and the "OMG, electricity will kill you" crowds that don't care if you're an apprentice who is working towards getting licensed or a character from Idiocracy. Frankly, once you understand how electricity works, everything else is pretty much common sense, math, and the simple act of looking up tables/charts and local regulations.
That said, as it relates to the OP, my success story:
For my control panel, I utilized an existing, dedicated 240-30A circuit intended for an electric clothes dryer (I have gas appliances now, so the circuit wasn't used). Fortunately, everything in my house runs through conduit (Chicago, of course), so it was simply a matter of moving equipment around to give the proper clearance/access to the sub-panel, planning & calculating a few EMT bends, securing the conduit to the floor joists, torquing the j-box connections properly, inspecting the existing wire/connections, decommissioning the old receptacle, and re-routing that wire to the spa panel that feeds my control panel. So while I didn't have to play in the main panel, a seemingly mundane project did involve quite a bit of planning and leg work (no pun intended) to ensure it was done correctly, and more importantly, to code. I could have done a shoddy install myself in under 30 minutes, but the whole thing - including research - took me 5-6 hours, although an experienced electrician could have probably done it in an hour.