I live in Switzerland and I just went through this process, opening a repair shop in January 2022. I work alone in a small workshop with very cheap rent in a village on the edge of a large city. I've sold a few custom-assembled bikes, but I don't sell bikes and I make almost nothing from the small range of accessories that I stock. Almost all the income is through repairs.
I'd previously worked in 2 of the larger bike shops in the region in 2011-2019. In 2020-21, I was occasionally doing repairs and custom builds for friends, working out of my basement, so I was stepping up from that by opening a proper workshop. My large network of contacts in the local bike community certainly helped a lot, and then I've had a decent amount of business from the local community where the shop is.
After being open for 6 months, I was able to recover the money I invested in setting up the shop. Fortunately, I already owned 90% of the tools including some of the specialist ones. I also had some of the furniture for the shop or got things from friends/second hand. Even so, initial outlay was significant and more than I'd hoped.
It wouldn't have worked as well if I didn't have knowledge of what I would need to buy for stock based on working in local shops for so well and already knowing some of my clientele. Also, Swiss Post is very good, so orders from local distributors arrive the next day (if they have stock), some orders I have to place with German websites, with about 1 week delivery, which often means I don't always make a lot of margin on parts.
Fortunately, my wife is the main earner in the family. Without that, my modest income wouldn't be enough. I have pretty low profit goals, but I have been able to meet/exceed them each month so far, but there is a lot of uncertainty all the time and not a lot of profit involved.
I haven't regretted it yet, but it's only worked out because of many factors in my favor. I wouldn't recommend it to many people except in certain situations.
I'm very happy working by myself and I can figure out all the administration stuff. I don't mind making less money than I could do worry-free being a salaried mechanic in a local shop. The income will hopefully improve in coming years, but even in the 1st year it's been enough to make it worthwhile.
Good luck! Here's my website:
https://ridefar.ch/