Funny to you, but very irritating to me most of the time, I've also had a similar experience on whale casino where I was given around 70 free spin, same also with Betfury where I was given 40 free spins, on each of this experiences, I thought within myself that there was no way I was going to spin all 70 or 40 free spins without winning something good, but to my greatest surprise, I spinned all 70 free spins on whale casino and made less than $3, and on Betfury, I ended up with less than a dollar win after using the entire 40 free spins, it made me very angry and actually did conclude that slot games are sometimes programmed to not give the gambler any winning, most especially when using free spins to play, maybe that is why they casino usually will specify which slot game in particular the free spins applies to/with.
Just as the name implies free spin, means that it is a bonus from the casino and each bonus has its level of rewards, what we should know is that casino bonuses are meant just to be wasted on the casino and not to make the gambler any money, so you are even lucky to have made the 3 dollar's from the 70 free spins that whale casino offered you, what I have settled with is that, if you interested in making some money and you trust you gaming skills to win then you should only depend on your deposits to gamble with, and also to avoid anything free offer's since most of those offers come with loads of requirements to be met before one could withdraw if you are lucky to win from them.
Many casinos even non bitcoin ones pay out on bonuses like that. I've had several friends who have won big on free signup bonuses. Apparently you haven't heard of false advertising, its illegal, and most places don't do this. Sure doesn't make me want to deposit there at all with that little game they play.
How come so many other casinos don't do this shady practice and actually pay out from free spins?