Sure, but you could say that a businessman (or more to the point a top decision maker for a football club, because that's what is more relevant than his general business acumen) doesn't make a lot of the decisions Levy has done of late. He's not in the greatest form. I also think there's probably a bit more nuance to Levy than this detached, emotionless accountant that only cares about the bottom line as the media present him. That Levy probably does grasp at 50 million. I think he'll be a little more personally invested in this decision and won't just fold to whatever fee is on the table.
I also disagree with the way you view the finances. The wages are not hugely relevant, it's an ongoing cost for services rendered. They'll be paying anyone they sign up to do that job. And as for 50 million, it's expensive for a season but probably isn't an incredible premium on his value as a world class striker. There are other benefits involved. Attracting a manager here and now. Finishing better next season. Retaining a 1% hope he can persuade Harry to be very dumb and sign again.
When it's 80 million those benefits of hanging on are probably less and less easy to entertain for Levy. No doubt about it, we'll have to grasp Harry Kane and be determined about it if we want him this summer, it's not going to be easy or cheap.