Don't know about Italy, but in the U.S., many bike shops trying to stay in business in the face of increasingly razor-thin margins have trouble finding and holding onto young employees, many of whom can find better-paying jobs elsewhere. Love of bikes can keep bike shop workers around only so long until they need to make a decent living wage. That might be opening a door for retirees who like the idea of keeping busy by working on bikes.
Maybe that's the case in bike shops in Italy, too. If there's a shop where you've established or can establish a relationship with the owner, you might consider talking to that owner about the possibliity of working there, even if it's only part time and only doing simple repair jobs, at least at first. You'd learn a lot about the bike business on the front lines and be better equipped to evaluate the practicality of the idea of opening your home-based repair business.