All of which might be reasons why Spurs often seems to fall just short. But it's hardly mismanagement, surely? Even less so, evidence of a "fuck up of a club".
The only players Spurs have sold who they didn't want to sell over the past 15 years or so are Carrick, Berbatov, Modric and Bale. Four players. Over a long period. And all back during a time when Spurs were nowhere near the level of the clubs who were buying from them. We're talking about clubs at the very top of the food chain - Man Utd (though less so now, obviously) and Real Madrid. There are barely more than two or three clubs in the world who can persuade their players to reject advances from those two. Thus keeping the aforementioned players and, importantly, keeping them happy would have been nigh on impossible. So, in each case, Levy did the next best thing by extracting maximum value.
As to Levy being a businessman first and a fan second, we had it the other way around with Irving Scholar back in the late 80's. And the club nearly went under. So long as Spurs' best interests and Levy's are equally served by the same strategy - and by and large during his stewardship of the club, they have been - then, in the absence of a superrich benefactor with a good plan, there's no one else I'd rather have steering the club.