Many people approach the whole topic of vermiculture as a way to make a quick buck.
Now, because everyone wants to make a quick buck many people are attracted to this idea. It is often offered in terms of turning rubbish into money and there are guarantees on the buy prices offered. This really needs to be looked at in terms of outwork at slavery rates of pay. There are successful large scale worm farms in existence and I am sure that there are people who will say I'm wrong because they are making money from vermiculture.
That said, people are being offered guaranteed incomes if they buy industrial size worms farms from worm farm makers. This is often about selling an overpriced worm farm rather than setting the buyer up with an independent income. If you are looking at this be very sceptical. If they are for real they should be able to produce existing clients who can show you that they are producing sufficient volume to justify the expence of the worm farm. An investment should return your capital to you within the working life of the machinery. Remember you have to take a cut from this for living expences.
Simply, if there was good money in worms I wouldn't be in shares. :)