I don't think we'll agree on this one mate. I don't believe Football works that way. If the player wanI'm not disputing that we were interested, but I don't think we were that interested. We could have had him at £70m, but weren't prepared to go any higher than £60m, which to me makes me think it was just posturing from the club to raise the profile of the club - "Look at us making massive bids for good players who the other top teams want too!". I don't believe we were ever seriously interested to get the deal done.
Also, if Zaha had stomped his feet enough, he would have got his move. Problem was, I just don't think he represented good value for us, Arsenal or any of the big European clubs at £60m, let alone £80m. There are better uses of money than Zaha, which is why in the end he knuckled down and stayed at Palace.
I somewhat agree with the point your making, however Zaha has contributed 20 goals and assists in an awful Palace team last season. That's in the same bracket as Eriksen and Sane and more than Son and Firmino. He's a cracking player, I just don't think he represents good value at £80m at his age, which is why it wouldn't surprise me if Richarlison went for the exact valuation you quoted there, £100m - assuming his trajectory continues.