I don't agree with the word " not possible". to be honest, free spins do not promise 100% winnings, i know that. But for some chances, you can get a lot of money from free spins feature.
I think you got the wrong side of my word bigger amount. I am not saying that you are spinning free spins for years. I was taking bigger amount in one spin.
Means you can not win a big amount in one spin. For big amount you will spin thousands of spins than you will get this. But again you will not sure about that the withdraw is possible or not.
Usually non-consistent results during free spins bonuses, the amount user can win is capped around 500x, from my personal experience. Hard to believe the house doesn't limit the winnings since the base bets are mostly less than $0.5. Imagine getting free spin bonus in most volatile slots like Tombstone Rip by NLC slot provider and hitting multiplier above 100kx. Btw max win is limited to 300kX per round in such slots, anyways imagine hitting such multi then quit gambling.
I think that depends on each user personal experience,me despite not winning from a long time I have won before several times x2000-x3000 in Play n Go provider although nowadays this provider is offering casinos changeable RTP which I believe has made me not winning anything more than x400 in my best win from the latest session and latest free spins from Green Knight slot.
I think there are people who have hit it big in No Limit City which is notorious for their huge max wins that other providers lack most of the time but as you said it is extremely difficult to get such high multipliers without playing for a long time in such slots.