The business model that consists in selling a subscription to be able to query a LLM isn't much of one: it's a race to the bottom. Users will switch as soon as anything even slightly better is out (like cancelling ChatGPT and taking a Claude 3 Opus subscription), companies with similarly performing models have to compete on price. It's ugly.
By making models freely available and by buying and advertizing that they bought a shitload of NVidia GPUs to train AI models (LLMs and others), Meta is adding additional pressure to those already fighting in an overcrowded market.
They don't do it because they'd suddenly be nice: Meta is still a despicable company with despicable tactics. It's all about screwing these one-trick ponies as much as they can: last thing Meta would want would be a tiny player to become a trillion behemoth.