Bit of a head fxxk to be fair! The idea of building a bike is paramount. Been annoying myself for ages now as things go wrong and can kind of see how to sort it out but too nervous to!!! Think if I build one then it should make more sense. Can't actually afford anything more at the moment anyway and this might keep me busy! However, also can't afford to waste money, so if this is destined to fail, I need to know now!
Look at it this way.
You are not actually building a bike, you are sourcing components and assembling one.
That is not going to beat you if you are able to keep looking for suitable and affordable parts.
Now if you were talking about frame building then that would be a different matter.
I have built frames for custom choppers using old frames for the tube, threaded, and sized parts. I am currently putting together a design for a front drive recumbent tadpole trike. That will be scratch building the whole frame and then designing and making the driven and braked front hubs and other specialist components.
It may or may not come together depending on how far beyond my skills I am pushing the design.
Your assembly shouldn't be daunting for you. Just make sure you start a good component parts, and tools, list to check costs and availability. The frame is apparently a bargain (I wouldn't know) so it is probably worth getting anyway as it could be sold on if you change your mind, as can the rest of the tools and components.