@Loretta126 I think you're teaching your son a valuable lesson. But let's be careful. . .
I'm in the restaurant biz. We had a dude recently come in and ask for a discount as he's browsing at the menu. Like, wah?!? We were pretty dumbfounded. I mean, I wouldn't even do that if I were at a dirt road shack in Thailand, let alone a nice restaurant in San Diego.
Does the Marriott provide audience to discount requests from Joe Blow/Jane Doe for a 3-night stay?
The lesson is a good one, when taught with grace/restraint. And asking for discounts on Airbnb is a place where you definitely want to exercise that grace/restraint. The more guests that get responses like @Ann72 gave, the better off the whole community will be. And when you grant discounts? It can lead to entitlement, or worse (as others have mentioned), crappy guests once they arrive.
I actually found @Ann72's response rather reserved. I'm pretty edgy when people ask for discounts ("If you don't feel like the home is a good value at it's current price, then there's likely no way that we will be able to meet your lofty expectations. So it's hard for us to see this working out, etc.). And like the example above, about 25% book the place in the face of my quippy reply anyway. Then sadly, a higher proportion of those people end up being tougher guests.