Plenty of philosophers over the centuries have thought long and hard about the free will problem, and not all of them have come out on the side of it existing. David Hume, for instance, had to resort to religion to solve his issues with it (God made us have free will), and several contemporary philosophers have come down firmly on the “deterministic but complex enough to look non-deterministic” side of the fence. in essence, that free will is an illusion, but a good enough one that we still feel like we have it.