Raising earthworms is a very simple process if you know how and where to raise them. Many people raise them indoors which is ok however, you can only raise so many in doors and you won't have enough to last a whole fishing season.
You will learn how to raise them outdoors so you can raise more and have plenty for you and your friends for the whole season. Indoor bins are usually 2 feet by 2 feet and 3 feet deep. They use shredded newspaper for the bedding and then you have to feed them every other day with garbage like banana skins, vegetable skins, coffee grounds and just about anything that you would throw away classified as garbage. Now this is ok but it is a lot of extra work. Also, raising them in shredded paper obviously is not natural for them so their shelf life probably wouldn't be as long either.
So the extra work for gathering food and feeding every 2 days is a deterrent for a lot of people who simply don't have time. Now don't forget the hassle of getting shredded paper which has no color in the ink because it will poison the worms. Only black ink will work if you want your worms to survive so separating the paper can be a major hassle in growing indoors as well. Besides, who wants a worm bed in your house? I know a lot of spouses that wouldn't allow that to begin with. Eliminate that issue at home and all of the extra work of raising indoor worms. Raise your worms outdoors in a natural environment which is better for them as well. Learn my simple technique for raising worms with very little effort.