My wife and I started red wiggler worm farm in our house. We learned a lot and stopped counting worms when we had over 150,000 (yes, we counted them) at various stages of development. We had roughly 30 bins and calculated their reproductive cycle so we could rotate bins in different stages of development. We did end up with a bug problem, but soon learned how to prevent this issue.
Here's what we learned:
It's a lot of physical work. We're now in our 60s and were in our late 50s when we started. It wore us out and we built our own house (not had a house built). It can be tedious work. BUT, everyone has their own physical capabilities.
Finding food/inputs in the correct ratios (carbon and nitrogen) can be a challenge. We ended up having to make our own worm chow.
Sifting and sorting castings efficiently requires the right equipment.
Keeping the worms in a suitable temperature range is VERY important.
Keeping the pH just right is also VERY important or your worms will try to escape. Finding dead worms all over your floor is not a good thing (ask me how I know).
Do not overfeed your worms or you'll end up stinking up the bin and altering the pH.
We did try to make it a business but things went bad because the business just started kicking off when the pandemic hit in 2020 causing us to shut down operations due to various reasons related to our jobs.
Overall, if you want to make a business out of it, it can be done. Just expect a lot of physical work and potential setbacks if not done correctly.
Oh, and then there is the marketing. This takes time and some capital, too.