Educate me on seed saving

Hello all, hope everyone has had a successful harvest and for those not done yet, hopefully everything works out for you guys in a timely manner. I know im probably not the first to ponder this, but ive been wondering why there are almost no farmers who save seed to plant the following year. I fully understand the issues of second generation hybrid offspring not carrying the desired traits of the parent generation, as well as the legal issues of saving seed with patented technology. Also I read that gmo second generation seeds can also lose desired traits. What I am wondering though is with margins as tight as they are, would it be cost effective to use seed that i guess would be considered an heirloom variety that would give consistent seed year after year? I understand the yeild would be lower, but I was wondering if anyone has crunched the numbers to see if it would be worth it due to the high costs of seed. I have to imagine that with the precise fertilizing and chemical management we have today that good yields would still be achievable? Please note that I do not grow corn or soybeans so I could be misinformed, just wondering out loud here. Interested to hear everyones take on this, hopefully I have posted this in the right section. Thanks

Educate me on seed saving