We're glad you joined us!
It is true that raising chicks is more time intensive, and possibly more expensive than purchasing already laying (or close to laying) hens. However, it does have other advantages, which is why I prefer buying chicks to adult birds.
Firstly, with chicks, there is less risk of purchasing diseased birds. Chicks are so young that they haven't usually contracted many bacteria, viruses, or other pathogens. Older birds have been exposed to many more things, and have a greater chance of carrying illness. Older birds may also have developed unwanted behaviors, such as egg eating.
Also, older birds are more prone to being flighty, especially if they weren't handled much when young. If you are getting chickens mostly as egg producing machines, not necessarily pets/entertainment, then this isn't quite as much of a disadvantage. It is far easier, though, to work with animals that aren't terrified of you. A scared hen is stressed out, which means she doesn't lay as well, and birds in a panic are prone to hurting themselves on things. With chicks, you have the opportunity to handle and socialize them.
Another problem with older birds is availability. Hatcheries and breeders usually sell a wider variety of chicks than they do of adult birds. If you want a particular breed, especially a rarer one, you are more likely to be able to buy chicks than laying pullets.