I'm telling you, use my method of swapping soaps and shampoo's
unless you go to a dermatologist and get an actual diagnosis for why you have dandruff, then its the cheapest solution.
Not washing your hair is gross, and like Kent says, will lead to worse conditions. Having your head covered in psoriasis, fungus, black heads and worse will not lead to getting ass. It will lead to you paying more money on the back end of this "experiment", and most likely being stuck in misery while your head itches.
Did i mention how fucking gross it is to have greasy hair and your scalp covered in shit? Cause it is.
Also, one thing I forgot to mention above.
Massage your scalp fool, you want to promote healthy growth and breathing of your hair line. What this means is you need to brush your hair, but get to the scalp. It will hurt at first, especially if you haven't ever done this before, but after a day or two, it will feel amazing, sort of like how a q-tip feels in your ear after a hot shower.
I use a hair brush like this:
Lastly:
Don't take hair advice from someone that is going bald, its a pretty clear indication they don't know WTF they are talking about.
Figure out "why" you ave dandruff, like I said above, there are several reasons for dandruff. They are very specific reasons for suffering from it, the starting treatments are typically what I listed above, but they might vary slightly in the long run
Don't be afraid to shave that shit off with no guard on the clippers so you can actually see your scalp. and get a picture of whats wrong.
Cool Story time:
I have insanely thick hair, I also have pretty bad dandruff
You would never know it, even if you were to put me under a black light, as I take care of my shit in the ways I listed above