However, using this approach, when something goes wrong (as inevitably will happen with all machines, mechanical or digital) my reaction would most likely be be to look down at the problem, scratch my head, then walk my ass to the bike shop.
You could just learn to maintain/repair the store bike, which has after all been designed to work by someone, and probably does most of the time. I've ridden bikes for years and only replaced things as they wear. Not that there's anything wrong with building your bike from scratch, but it's not an automatic guarantee of superiority.
You could just learn to maintain/repair the store bike
Personally, I find Ubuntu like a store-bought bike that uses a bunch of non-standard parts. You may have a complete tool kit, but you don't have the right tool for this bike.
Or: when I troubleshoot Ubuntu, I learn Ubuntu. When I troubleshoot Arch, I learn Linux.
You could just learn to maintain/repair the store bike, which has after all been designed to work by someone, and probably does most of the time. I've ridden bikes for years and only replaced things as they wear. Not that there's anything wrong with building your bike from scratch, but it's not an automatic guarantee of superiority.