AITA for refusing to purchase something expensive just because my 3yo wants it?

I have a 3yo son and I'm a single dad. My son has been begging me for a gaming chair for a while now. He saw it on an ad and kept asking me for it. I told him we're not getting it because he's too young to have one and we don't have the money for it. He recently asked me again, so I decided to get it for him.<br><br>I went to the store and picked up the gaming chair. It was $100, and even though that's a bit expensive for me, I'm willing to do it for my son. Now here is the part where I might be the AH. When I was in the store with my son, he chose one chair, but when we got to the cashier, he said he wanted another one. I told him that he was going to put the other one back because we're not going to buy two.<br><br>He started screaming and crying because he wanted the second chair. I told him that we can't buy two and we already have the first one. He said he wants me to buy the other one, and I said I don't want it because it's more expensive. He said he's going to cry louder. I told him we're leaving the store and not buying the first one either because he's being too demanding and throwing a tantrum.<br><br>The cashier said I should buy both because my son wants them. I said that I'm not going to spend that much money just because my 3yo is demanding it. She said that he knows we can afford it and that I'm being a bad dad by not buying what he wants. She also said that it's just a gaming chair and she's disappointed in me.<br><br>AITA for refusing to buy my 3yo son a gaming chair because he threw a tantrum in the store?