WOW 4%? What site gives that! Because it sure as shit isnt this one lol. It's 0.04% NOT 4% hahahaha. The day this shithole gives 4% is the day I retire and finally achieve my goal of having referral income be enough to reitre on. All the "extra" crap should be removed and the referral income increased as a result.
Lending BTC in general never really gave huge returns compared to say lending USD on Bitfinex margin loans. The only time I can remember when lending BTC was profitable was maybe in the short period when alts were rallying and people were selling BTC in exchange for alts. Then people lent out their BTC on interest and those were used to buy an alt ratio.
Most people who frequent a gambling site are not interested in 4% gains, you can get that with a stock or with a savings account. People who go on gambling sites want 100-1000% profits instead and its one of the reason why gambling is considered very high risk and very high reward if done correctly.
However most people get emotional and bet too much and they end up getting cleaned out due to greed and fear.