It means Juve will continue to lose market share in the future, which means they will be selling more and more players and be unable to compete. Higuain doesnt provide commercial revenues unlike Pogba who can recuperate the price, Higuain is almost 29 and he has a rapidly declining sell-on value. Scoring goals against Sassuolo means nothing when the price is as absurd as it is.
The Higuain transfer did exactly that: Being able to not only compete but more importantly dominate in Serie A for another 3-4 years, the resulting revenues for Scudetto and CL will further finance their wage structure and future signings aswell as making the club attractive to future potential signings. The best way to be succesful in the future is to be already being succesful in the present and signing high profile players will ensure exactly that. If Barca were to sign Suarez again today, would you also be saying it's a bad deal? Probably not, because he upgrades your squad and that ensures sportive success which still is the preferred source of income to reselling players. Especially if Suarez would have been already carrying one of your biggest domestic rivals like Atletico for in the past 3-4 years.
Juve hasn't been really dependend on sell-on values anyway. If you were to say so the "swap" came with additional 15m transfer profit, future additional revenues for CL and Serie A (-champions), PLUS an additional annual wage savings of the diffrence between Higuains wage
now (€7.7m) to the one Juventus would have had to use to match Utds voluminous
€17.8m bid (also resulting in everyone else wanting fancy contracts too,
THEN Juve would be dependend on sell-values.)