If your net expense of drafting is $13/week then you're either getting ripped off or losing every game and going out of your way to avoid picking any valuable cards. It's been a few years since I last played, but when I did draft weekly I averaged well over $5 of cards per draft without explicitly money-drafting anything that didn't pay for the draft by itself. The median draft leaves you with a few $1 rares, but there's enough high outliers to pull the mean up quite a bit.

It's pretty dishonest to discount the cost of drafting because you get some high-value cards while refusing to discount the cost of constructed... the entire cost of constructed is obtaining high-value cards. If you buy a $400 deck, do $200 of maintenance on it over one year, and then sell your cards at a 50% loss, you're still way ahead of a drafter who averaged $6 of money cards per week. And on top of all that, you had the option of playing more than once a week if you wanted to, and you never deliberately sabotaged yourself in the attempt to cut costs on your hobby ("explicitly money-drafting anything that [paid] for the draft").

I might also note that on Magic Online, it's definitely not true that the median draft leaves you with a few $1 rares, as the residual value that bad rares used to have has been cannibalized by mythic rares. A bad rare in MTGO can be purchased for $0.10; obviously you can sell it for less than that. Are paper rares that much more valuable?