Longhairgirl makes some good points
what passes for a "business" in many cases is only a cleaning business. From what I heard, the hours put in, the abuse to your body and exposure to chemicals, the small amount of money plus the trouble with the internal revenue service because you are "self-employed" makes this undesirable. I should also mention the fact that most people had to get out of this when they hit middle age because they just could not do it anymore.
But I have to agree with truthsetsonefree:
I think that also comes from trying to meet all of the demands WT puts on them. ........... Unfortunately it burns them because having your own business usually involves more committment to make it work. Something that gets in the way of all of the WT activities.
A fair statement would be that there is nothing wrong with starting your own cleaning business while you have the energy. You need to be careful about exposure to chemicals. Also, owning your own business requires that you dedicate enough time to it, not to a goofy religion. By the time you get older, you could either sell your business or grow your business to the point that you would be a boss.
The troubles mentioned by LHG happen often because people only give enough energy to the business to get by, so they can further the WTS profits goals. The IRS problem comes from inexperience as the tax advantages for a self-run business are pretty good if you run it out of your home and vehicle and phone. It can pay for computers, vehicle repairs, home needs, utilities, etc.
I just don't want to leave alone the statement that JW's self-employment goals are bad. They are pretty good, but these folks slave for two masters, the work and the Watchtower. That's the real problem. Also, getting an education or developing skills and saving money when you are younger would help instead of pioneer recruiting.