Because Sony is hardly making money on the PS4 and were losing money on the PS3. They weren't going to make the same mistake, a lot of their profit from the PS4 is coming straight from PS+ users. They could have always made the console weaker and worse to make some actual profit off of it and then not charged money for online services.

GTA V is coming to PS5 — and GTA Online will be free | Tom Jun 11, 2020 Sony explains why you'll have to pay for online with PS4 After being asked what went into the decision to charge for online gameplay, Sony explained that online features and services are going to be a "big pillar" of the PS4 experience. They go on to

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