Its only fun for them because they are ignorant and think they are going to find a strategy that works when they are just wasting their money
As a matter of facts, there are some strategy that "works" providing you know how to use it properly. The word strategy actually doesnt mean that it is solely based on "betting strategy" only as there are alot of other strategy to consider which is utilizing bonus / promotions .You may not be able to turn the edge into your favour however if you do it properly than you could atleast "lower" them.
Take an example of bustabit, with its bonus feature and the proper way to "get" it then you could even turn the edge into +EV . However this doesnt mean that it will always work. Simply because of the nature of gambling itself is pretty much based on luck as well so nothing is surely works for 100 % but that doesnt mean you will lose because turning it into +EV and do it in a proper way actually means you will get profit on the long run just not to be rich in overnight
Another example will be betterbets with its cashback bonus up to 20 % of the house edge, thats merely giving away 20 % of their house edge and player have the better chance to win and if you take close look at my calculation ( references below ). If you actually "utilize" this then your house edge is bound to be as low as 0.06 % which is near to zero and that means the probability for you to win is much higher in this case
Considering the luck forging will be making the house edge into 0.1 % and Happy Hour will be 0.25 % that means at platinum level membership, the House Edge will be dropped as low as 0.06 % for Luck Forging and 0.15 % for Happy hour