Free spins also sometimes don't give anything, I've had several free spins but didn't get anything, although I've also had big wins but mostly not, but when I buy free spins it's more possible to get a decent win and it's more exciting than the free spins that come from regular spins.
The experience is quite strange because here lies the probability, the spins that are purchased are more likely than the spins that are given for free.
I do not think that the frее spins have some great probability for winning than regular rotations. The slots are a very complex game that can easily delay and very quickly devastate your deposit if you get away and even more so if you put a high rate for rotation. I do not see the point of checking my luck in the slots, because here it is not only in luck and in the low probability, there are only a lot of players, but only a few will win, the rest will simply give their money so that the winners can divide them later, and the casino will take its share.