Success is difficult. It becomes increasingly difficult because: well, you know how to make a PC so you know how easy it is.
The problem is the market itself:
those who will appreciate custom PC manufacturing may already know how to do it themselves, so the market is quite small.
And those who don’t know better and only buy things from shelves … You won’t be able to compete with companies like DELL that have their own factories and produce their own components below the wholesale price you will pay (and that’s assuming you even can get wholesale prices)
And that’s the market volatility of custom PC manufacturing. There is only one small niche for people who 1) want a really special PC (not any cheap item), and 2) it won’t build it themselves.
Another big risk is inventory investment. Until you have a growing business that is able to maintain inventory, you always risk paying more for something that is only there and depreciating its value until (and if) you sell it.
business building a custom PC
Do you want to do business building a custom PC? I may suggest that you take that route to consider a broader business model. Unless you only want to do a few computers a year at the hobby level (like some people do on eBay and only sell a few computers a year), you will need lots of revenue streams.
For example, the most successful custom PC store I’ve ever seen does more than a custom PC. They are full retail stores that offer a variety of computer components and related peripherals (gaming chairs, computer desks, etc.). They will conduct audio installations specifically for home theaters, offer home IT solutions and run cables for optical fiber. They are complete service installers for smart home technology, and other tangent computer related services.
And do you know what makes the most money from them? Computer support and technical support. Replacing several male laptop screens, data recovery after system crashes, etc., etc.
So, you want to set up a special PC shop? Of course, realize that it will be a side business for what keeps your store alive and operational. Because you have to depend on local people so that you continue to do business with computer repairs and their IT needs. Your service will have value for your local community.
Compete only as a few random men who make PCs? What market? You don’t have online opportunities to get traction above the level of hobbies, unless you are able to invest millions to compete with big players.