I think one reason people quit is home brewing is not easy to get right on the first few batches. Especially if you are used to good quality craft beer. Your first few batches will not compare.Maybe, but who knocks pizza dough or bread out the park first time? Maybe risk/reward is high due to the amount of time.
I do brew to save money. Beer is stupid expensive right now. $6+ bombers, $10+ six packs, $7+ pints. If I factored the time at minimum wage, I'd still be saving on a 10 gallon batch. I think it is unfair to factor time when it is also my hobby. If i wasn't brewing, I'd be out spending or watching tv.
I think many people quit all kinds of things that are hard. Lots of people receive home brew equipment as a gift, give a try a few times and move on.
I agree home brewing is cheaper as long as you don't count the value of your time and probably you need to exclude equipment cost. The way I see it equipment and time are costs associated with my hobby. Ingredients, fuel, CO2 are costs associated with the beer.