I think you are looking at it the wrong way and my point that gambling is entertainment counters your other points.
Gambling is entertainment for most people but for some people gambling is a job. Poker players mostly but also some sports bettors or horse races bettors.
For example, if I login every day and roll 6 times and repeat this every day for about a year then I can finally withdraw a whopping 30,000 satoshi ($2). I find more money than that every week just walking to and from the store picking up change that is dropped on the ground.
If you play the free roll on your mobile you dont need to log in and takes seconds to play, so the relation between effort and reward is superior than walking to the store and picking up change.
Also, you can get some big prices, not only the minimum, so on average it is going to be more than $2, and if you are lucky much more than that.