There's far more to hardware than just designing the logic circuits (open source designs do exist such as Risc V) you also have to fabricate them and the proces

There's far more to hardware than just designing the logic circuits (open source designs do exist such as Risc V) you also have to fabricate them and the processes for fabricating CPU's, GPU's and similar chips are probably the most advanced of any technology, requiring equipment that costs millions to billions of dollars.